Measuring device, measuring system, moving body, and measuring method

ABSTRACT

A measuring device for measuring an inspection target on the basis of vibration generated when the inspection target has been irradiated with laser light includes a condensing position deriving portion configured to derive an amount of adjustment of a distance between condensing lenses of a laser condensing unit configured to condense the laser light on the basis of a distance between a laser device configured to radiate the laser light and an irradiation location of the laser light and a communicating portion configured to transmit control information including information representing the amount of adjustment to the laser condensing unit.

TECHNICAL FIELD

Embodiments of the present invention relate to a measuring device, ameasuring system, a moving body, and a measuring method.

Priority is claimed on Japanese Patent Application No. 2018-060867,filed Mar. 27, 2018, the content of which is incorporated herein byreference.

BACKGROUND ART

Maintenance work on infrastructure such as tunnels is performed byvisual checking and manual work (palpation, tapping, or knocking) bytechnicians. Thus, the maintenance work is significantly time-consumingand involves a great risk. Therefore, it is necessary to automate andimprove the maintenance work of infrastructure such as tunnels.

Regarding technology for inspecting for internal defects of concretestructures such as inner walls of a tunnel, a diagnostic method usinglaser-induced vibration waves has been proposed (for example, see PatentDocument 1).

According to the diagnostic method using laser-induced vibration waves,laser ablation is the most basic technique to impart vibration to asample and the sample irradiated with laser light is diagnosed on thebasis of vibration generated when the sample is irradiated with thelaser light. The laser ablation is a spraying or transpirationphenomenon when there is rapid heating of a sample or formation ofplasma by irradiation with a high-power laser pulse. The vibrationgenerated in the sample is measured by a device using laser measurementtechnology such as a laser Doppler vibrometer and a laserinterferometer. The vibration generated in the sample measured by thedevice using the laser measurement technology is represented by anamplitude waveform with respect to time. The amplitude waveform withrespect to time is transformed into a frequency spectrum of vibrationaccording to a Fourier transform. Because the number of vibrations of adefective location increases on the basis of a change in the frequencyspectrum of the vibration, it is possible to inspect a state of theinspection target such as whether an internal defect such as a cavityhas occurred.

CITATION LIST Patent Literature [Patent Document 1]

-   Japanese Unexamined Patent Application, First Publication No.    2013-29399

SUMMARY OF INVENTION Technical Problem

In outdoor measurement using laser-induced vibration waves, it isdifficult to implement high-speed and high-accuracy measurement becausethe measurement is strongly affected by a measurement environment. Forexample, environmental noise (ambient noise or an echo) causes noise inthe vibration spectrum, which may make appropriate laser irradiationdifficult due to irregularities at an irradiation location or thepresence or absence of an appendage.

The present invention has been made to solve the above problems and anobjective of the present invention is to provide a measuring device, ameasuring system, a moving device, and a measuring method capable ofimproving the accuracy of measurement if an inspection target ismeasured on the basis of vibration generated when the inspection targetwas irradiated with laser light.

Solution to Problem

(1) According to an aspect of the present invention, a measuring devicefor measuring an inspection target on the basis of vibration generatedwhen the inspection target has been irradiated with laser light, themeasuring device includes: a condensing position deriving portionconfigured to derive an amount of adjustment of a condensing position ofa laser condensing unit configured to condense the laser light on thebasis of the distance between a laser device configured to radiate thelaser light and an irradiation location of the laser light; and acommunicating portion configured to transmit control informationincluding information representing the amount of adjustment to the lasercondensing unit.

(2) According to an aspect of the present invention, the measuringdevice according to the above-described aspect (1) further includes anirradiation location analyzing portion configured to select a locationto be irradiated with the laser light on the basis of informationrepresenting an image of a location of the inspection target scheduledto be irradiated with the laser light, wherein the communicating portionis configured to transmit control information including informationrepresenting the location to be irradiated with the laser light selectedby the irradiation location analyzing portion to a sweep deviceconfigured to sweep the laser light.

(3) According to an aspect of the present invention, the measuringdevice according to the above-described aspect (1) or (2) furtherincludes a reverberation sound data acquiring portion configured toacquire time-series data of a reverberation sound generated when theinspection target has been irradiated with the laser light; and areverberation sound analyzing portion configured to acquire a timing atwhich the inspection target is irradiated with the laser light on thebasis of an intensity of the reverberation sound of the time-series dataof the reverberation sound acquired by the reverberation sound dataacquiring portion, wherein the communicating portion is configured totransmit control information including the information representing thetiming acquired by the reverberation sound analyzing portion to thelaser device configured to radiate the laser light.

(4) According to an aspect of the present invention, the measuringdevice according to any one of the above-described aspects (1) to (3)further includes a data removing portion configured to remove dataduring a predetermined time period from a time at which the inspectiontarget has been irradiated with the laser light from measurement data ofvibration generated in the inspection target.

(5) According to an aspect of the present invention, the measuringdevice according to any one of the above-described aspects (1) to (4)further includes a noise removing portion configured to remove noisefrom measurement data on the basis of the correlation coefficientbetween the measurement data of vibration generated in the inspectiontarget and an evaluation function of the measurement data.

(6) According to an aspect of the present invention, the measuringdevice according to any one of the above-described aspects (1) to (5)further includes a noise removing portion configured to remove noisefrom measurement data of vibration on the basis of the measurement dataof the vibration generated in the inspection target and data obtained byshifting a phase of time-series data of the measurement data.

(7) According to an aspect of the present invention, the measuringdevice according to any one of the above-described aspects (1) to (6)further includes a determining portion configured to determinefaultlessness of a location of the inspection target irradiated with thelaser light on the basis of measurement data acquired when vibration hasbeen induced in the inspection target by irradiating the inspectiontarget with the laser light and measurement data acquired when theinspection target has not been irradiated with the laser light thatinduces the vibration.

(8) According to an aspect of the present invention, in the measuringdevice according to any one of the above-described aspects (1) to (7),at least the laser condensing unit is stored in a housing havingsoundproofing performance.

(9) According to an aspect of the present invention, there is provided ameasuring system for measuring an inspection target on the basis ofvibration generated when the inspection target has been irradiated withlaser light, the measuring system including: an excitation laser deviceconfigured to radiate excitation laser light, which is the laser lightthat causes the inspection target to vibrate; an excitation lasercondensing unit configured to condense the excitation laser lightradiated by the excitation laser device; and a measuring deviceincluding a condensing position deriving portion configured to derive afirst amount of adjustment of a condensing position of the excitationlaser condensing unit on the basis of a distance between the excitationlaser device and an irradiation location of the excitation laser lightradiated by the excitation laser device; and a communicating portionconfigured to transmit control information including informationrepresenting the first amount of adjustment to the excitation lasercondensing unit.

(10) According to an aspect of the present invention, the measuringsystem according to the above-described aspect (9) includes ameasurement laser device configured to irradiate the inspection targetwith measurement laser light that is laser light for detecting vibrationinduced in the inspection target; and a measurement laser condensingunit configured to condense the measurement laser light radiated by themeasurement laser device, wherein the condensing position derivingportion derives a second amount of adjustment of a condensing positionof the measurement laser condensing unit on the basis of a distancebetween the measurement laser device and an irradiation location of themeasurement laser light radiated by the measurement laser device andwherein the communicating portion is configured to transmit controlinformation including information representing the second amount ofadjustment to the measurement laser condensing unit.

(11) According to an aspect of the present invention, the measuringsystem according to the above-described aspect (10) includes a sweepdevice configured to sweep the excitation laser light output by theexcitation laser device and the measurement laser light output by themeasurement laser light device.

(12) According to an aspect of the present invention, in the measuringsystem according to any one of the above-described aspects (9) to (11),at least the excitation laser condensing unit is stored in a housinghaving soundproofing performance.

(13) According to an aspect of the present invention, there is provideda moving body equipped with the measuring system according to any one ofthe above-described aspects (9) to (11).

(14) According to an aspect of the present invention, there is provideda measuring method to be executed by a measuring device for measuring aninspection target on the basis of vibration generated when theinspection target has been irradiated with laser light, the measuringmethod including steps of: deriving an amount of adjustment of acondensing position of a laser condensing unit configured to condensethe laser light on the basis of a distance between a laser deviceconfigured to radiate the laser light and an irradiation location of thelaser light; and transmitting control information including informationrepresenting the amount of adjustment to the laser condensing unit.

(15) According to an aspect of the present invention, the measuringmethod according to the above-described aspect (14) further includessteps of: selecting a location to be irradiated with the laser light onthe basis of information representing an image of a location of theinspection target scheduled to be irradiated with the laser light; andtransmitting control information including information representing thelocation to be irradiated with the laser light to a sweep deviceconfigured to sweep the laser light.

(16) According to an aspect of the present invention, the measuringmethod according to the above-described aspect (14) or (15) furtherincludes steps of: acquiring time-series data of a reverberation soundgenerated when the inspection target has been irradiated with the laserlight at a certain timing; acquiring a timing at which the inspectiontarget is irradiated with the laser light on the basis of an intensityof the reverberation sound of the time-series data of the reverberationsound; and transmitting control information including the informationrepresenting the timing to the laser device configured to radiate thelaser light.

(17) According to an aspect of the present invention, the measuringmethod according to any one of the above-described aspects (14) to (16)further includes a step of removing data during a predetermined timeperiod from a time at which the inspection target has been irradiatedwith the laser light from measurement data of vibration generated in theinspection target.

(18) According to an aspect of the present invention, the measuringmethod according to any one of the above-described aspects (14) to (17)further includes a step of removing noise from measurement data on thebasis of a correlation coefficient between the measurement data ofvibration generated in the inspection target and an evaluation functionof the measurement data.

(19) According to an aspect of the present invention, the measuringmethod according to any one of the above-described aspects (14) to (18)further includes a step of removing noise from measurement data ofvibration on the basis of the measurement data of the vibrationgenerated in the inspection target and data obtained by shifting a phaseof time-series data of the measurement data.

(20) According to an aspect of the present invention, the measuringmethod according to any one of the above-described aspects (14) to (19)further includes a step of determining faultlessness of a location ofthe inspection target irradiated with the laser light on the basis ofmeasurement data acquired when vibration has been induced in theinspection target by irradiating the inspection target with the laserlight and measurement data acquired when the inspection target has notbeen irradiated with the laser light that induces the vibration.

Advantageous Effects of Invention

According to embodiments of the present invention, the accuracy ofmeasurement can be improved if an inspection target is measured on thebasis of vibration generated when the inspection target has beenirradiated with laser light.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing an example of a laser-induced vibration wavemeasuring system of a first embodiment.

FIG. 2 is a conceptual diagram of sweeping of the laser-inducedvibration wave measuring system of the first embodiment.

FIG. 3A is a diagram showing an example of a frequency spectrum ofinduced vibration obtained by a processing unit of the laser-inducedvibration wave measuring system of the first embodiment.

FIG. 3B is a diagram showing an example of a frequency spectrum ofinduced vibration obtained by the processing unit of the laser-inducedvibration wave measuring system of the first embodiment.

FIG. 4 is a block diagram showing an example of the processing unit ofthe laser-induced vibration wave measuring system of the firstembodiment.

FIG. 5 is a diagram showing an example of a scheduled laser irradiationlocation image.

FIG. 6 is a diagram showing an example (part 1) of sound information.

FIG. 7A is a diagram showing an example (part 2) of sound information.

FIG. 7B is a diagram showing an example (part 2) of sound information.

FIG. 8A is a diagram showing an example (part 3) of sound information.

FIG. 8B is a diagram showing an example (part 3) of sound information.

FIG. 9A is a diagram showing an effect of noise removal of thelaser-induced vibration wave measuring system of the first embodiment.

FIG. 9B is a diagram showing an effect of noise removal of thelaser-induced vibration wave measuring system of the first embodiment.

FIG. 10 is a diagram showing an example of noise removal of thelaser-induced vibration wave measuring system of the first embodiment.

FIG. 11 is a diagram showing an example of vibration data acquired bythe laser-induced vibration wave measuring system of the firstembodiment.

FIG. 12 is a diagram showing an effect of the laser-induced vibrationwave measuring system of the first embodiment removing unexpectedlygenerated noise.

FIG. 13A is a diagram showing an example of a frequency spectrumdetermined by the laser-induced vibration wave measuring system of thefirst embodiment.

FIG. 13B is a diagram showing an example of a frequency spectrumdetermined by the laser-induced vibration wave measuring system of thefirst embodiment.

FIG. 14 is a sequence chart showing an example (part 1) of an operationof the laser-induced vibration wave measuring system of the firstembodiment.

FIG. 15 is a sequence chart showing an example (part 2) of an operationof the laser-induced vibration wave measuring system of the firstembodiment.

FIG. 16 is a sequence chart showing an example (part 3) of an operationof the laser-induced vibration wave measuring system of the firstembodiment.

FIG. 17 is a flow chart showing an example (part 4) of an operation ofthe laser-induced vibration wave measuring system of the firstembodiment.

FIG. 18 is a block diagram showing an example of a processing unit of alaser-induced vibration wave measuring system of a second embodiment.

FIG. 19 is a diagram showing an example of noise removal of thelaser-induced vibration wave measuring system of the first embodiment.

FIG. 20 is a diagram showing Example 1 of a laser-induced vibration wavemeasuring system of Modified Example 1 of the first embodiment.

FIG. 21 is a diagram showing Example 2 of the laser-induced vibrationwave measuring system of Modified Example 1 of the first embodiment.

FIG. 22 is a diagram showing Example 3 of the laser-induced vibrationwave measuring system of Modified Example 1 of the first embodiment.

FIG. 23A is a diagram showing a side view of a laser light port LP ofthe laser-induced vibration wave measuring system of Modified Example 1of the first embodiment.

FIG. 23B is a diagram showing a front view of the laser light port LP ofthe laser-induced vibration wave measuring system of Modified Example 1of the first embodiment.

FIG. 24 is a diagram showing a minimum angle of installation angles of alaser window LW.

FIG. 25 is a diagram showing a maximum angle of the installation anglesof the laser window LW.

FIG. 26 is a diagram showing an example of a laser-induced vibrationwave measuring system of Modified Example 2 of the first embodiment.

FIG. 27A is a diagram showing an example of a laser-induced vibrationwave measuring system of Modified Example 3 of the first embodiment.

FIG. 27B is a partially enlarged view of the laser-induced vibrationwave measuring system of Modified Example 3 of the first embodiment.

FIG. 28A is a diagram showing Example 1 of the effect of a soundproofwall of the laser-induced vibration wave measuring system of ModifiedExample 3 of the first embodiment.

FIG. 28B is a diagram showing Example 2 of the effect of a soundproofwall of the laser-induced vibration wave measuring system of ModifiedExample 3 of the first embodiment.

FIG. 29 is a diagram showing Example 3 of the effect of a soundproofwall of the laser-induced vibration wave measuring system of ModifiedExample 3 of the first embodiment.

FIG. 30 is a sequence chart showing an example of an operation of thelaser-induced vibration wave measuring system of the first embodiment.

FIG. 31 is a sequence chart showing an example of an operation of thelaser-induced vibration wave measuring system of the first embodiment.

DESCRIPTION OF EMBODIMENTS

Next, a measuring device, a measuring system, a moving body, and ameasuring method of the present embodiment will be described withreference to the drawings. The embodiments to be described below aremerely examples and the embodiments to which the present invention isapplied are not limited to the following embodiments.

Also, in all the drawings showing the embodiments, the same referencesigns are used for components having the same functions and a redundantdescription will be omitted.

Also, the term “based on XX” mentioned in the present application means“based on at least XX” and also includes a case based on another elementin addition to XX. Also, the term “based on XX” is not limited to a casein which XX is directly used and includes a case based on calculation orprocessing performed on XX. “XX” is any element (for example, anyinformation).

According to the present embodiment, when high-speed measurement isperformed in an outdoor space (where an environment is not constant), ameasuring device performs the measurement while excluding a cause ofdeterioration in the accuracy of measurement such as a “change in adistance between a laser irradiation portion and a measurement target,”a “change in a measurement target surface,” or “unexpected noise,” whichcauses a measurement error, in real time. The measuring device canmeasure an inspection target M using the fact that vibration induced byan excitation laser changes according to a state of a laser irradiationlocation. Here, the inspection target is a sample prepared on the basisof a standard for various types of performance tests such as strengthand resistance. It is possible to measure a structure (an internalcavity or a crack propagation direction) that is not easily ascertainedfrom the exterior of the inspection target M. For example, the measuringdevice is suitable for measuring an infrastructure structure mainlycomposed of concrete. Also, because it is possible to perform quickmeasurement, the measuring device is suitable for performing detailedmeasurement or wide-range measurement with respect to measurement of,for example, tunnels, bridges, and the like.

First Embodiment (Laser-Induced Vibration Wave Measuring System)

FIG. 1 is a diagram showing an example of a laser-induced vibration wavemeasuring system of the first embodiment. In FIG. 1 , a solid linerepresents an optical path and a broken line represents a signal line.

A laser-induced vibration wave measuring system 20 measures aninspection target M on the basis of vibration generated when theinspection target M has been irradiated with laser light. Thelaser-induced vibration wave measuring system 20 includes an excitationlaser device 1, a measurement laser device 2, a galvano scanner unit 3,a biaxial mirror unit 5, a reverberation sound monitor 7, a mirror 8 a,a mirror 8 b, and a mirror 8 c, a distance measurement laser device 9,an excitation laser condensing unit 10, a measurement laser condensingunit 11, an imaging device 13, and a processing unit 100.

The excitation laser device 1 outputs a high-power laser pulse and theinspection target M is irradiated with the output high-power laserpulse. Thereby, vibration is generated (induced) in the inspectiontarget M. Exemplary examples of the excitation laser device 1 are ahigh-power pulse laser and a Q-switch Nd:YAG laser.

The measurement laser device 2 detects vibration induced in theinspection target M. The measurement laser device 2 generates laserlight (hereinafter referred to as “measurement laser light”) fordetecting vibration induced in the inspection target M and outputs thegenerated measurement laser light. The measurement laser device 2acquires the laser light reflected or scattered by the inspection targetM and converts the acquired laser light into the number of vibrationssuch as an amount of displacement or a variation speed. The measurementlaser device 2 outputs information representing the number of vibrationsobtained by converting the laser light to the processing unit 100. Anexample of the measurement laser device 2 is a laser interferometer, alaser Doppler vibrometer, or the like. Here, because information isobtained as an amount of displacement if the measurement laser device 2is a laser interferometer and is obtained as a velocity if themeasurement laser device 2 is a laser Doppler vibration, suchinformation is converted into the number of vibrations. Also, although ameasuring device using a laser will be described as an example, thepresent invention is not limited thereto as long as the vibrationinduced in the inspection target M can be detected.

The distance measurement laser device 9 measures a distance between thedistance measurement laser device 9 and the inspection target M(hereinafter referred to as an “irradiation distance”) and outputsinformation representing the irradiation distance obtained through themeasurement to the processing unit 100. A conventionally well-knowndevice can be used as the distance measurement laser device 9 withoutparticular limitation. Although a distance measuring device using laserlight will be described below as an example, the distance measuringdevice is not limited thereto as long as the irradiation distance can bemeasured.

The galvano scanner unit 3 and the biaxial mirror unit 5 sweep laserlight output by the excitation laser device 1 (hereinafter referred toas “excitation laser light”), measurement laser light output by themeasurement laser device 2, and laser light output from the distancemeasurement laser device 9 (hereinafter referred to as “distancemeasurement laser light”). Also, although a combination of the galvanoscanner unit 3 and the biaxial mirror unit 5 will be described as anexample of a mechanism for sweeping the excitation laser light, themeasurement laser light, and the distance measurement laser light, sucha laser light sweep mechanism is not limited to the combination of thegalvano scanner unit 3 and the biaxial mirror unit 5 as long as at leastone of the excitation laser light, the measurement laser light, and thedistance measurement laser light can be swept.

The reverberation sound monitor 7 acquires time-series data of a sound(hereinafter referred to as a “reverberation sound”) in which anexplosion sound generated by ablation of the surface of the inspectiontarget M enters the reverberation sound monitor 7 and is superimposed ona signal waveform as noise. Specifically, the reverberation soundmonitor 7 measures an intensity of the sound generated by irradiatingthe inspection target M with either or both of the excitation laserlight and the measurement laser light and outputs sound informationobtained by measuring the intensity of the sound to the processing unit100.

For example, the reverberation sound monitor 7 is implemented byconverting a sound measured using a so-called acoustic measuring devicesuch as a microphone into an electrical signal. Alternatively, vibrationof the measuring device (typically a part of the measuring device)caused by the reverberation sound may be measured by an accelerationsensor and sound information of the reverberation sound may be acquired.Also, the reverberation sound measured by the reverberation soundmonitor 7 is not limited to a sound of an audible frequency (forexample, 20 Hz to 20 kHz) and includes so-called ultrasonic waves havinga frequency of 20 kHz or higher. It is only necessary to measure afrequency having an influence on the measurement of the vibration of theinspection target M induced by the excitation laser as the reverberationsound.

An installation place of the reverberation sound monitor 7 is notparticularly limited as long as the reverberation sound can be measured.In FIG. 1 , the reverberation sound monitor 7 is attached to a biaxialmirror unit 5. In the present embodiment, a description will continuewith a case in which the reverberation sound monitor 7 acquires a soundgenerated by irradiating the inspection target M with the excitationlaser light. By attaching the reverberation sound monitor 7 to thebiaxial mirror unit 5, the sound can be measured at the closest positionwhere the inspection target M is irradiated with the excitation laserlight.

The mirror 8 a bends an optical path of the excitation laser lightoutput from the excitation laser device 1 at a 90-degree angle. Themirror 8 b bends an optical path of the distance measurement laser lightoutput from the distance measurement laser device 9 at a 90-degreeangle.

The excitation laser condensing unit 10 condenses the excitation laserlight output by the excitation laser device 1. The excitation lasercondensing unit 10 includes a lens 12 a and a lens 12 b for condensingthe excitation laser light.

The mirror 8 c bends an optical path of the excitation laser lightcondensed by the excitation laser condensing unit 10 at a 90-degreeangle.

The measurement laser condensing unit 11 condenses the measurement laserlight output by the measurement laser device 2. The measurement lasercondensing unit 11 includes a lens 12 c and a lens 12 d for condensingthe measurement laser light.

The imaging device 13 is attached to the biaxial mirror unit 5 andimages a location of the inspection target M scheduled to be irradiatedwith the laser light. The imaging device 13 outputs informationrepresenting an image of the location of the inspection target Mscheduled to be irradiated with the laser light obtained through imagingto the processing unit 100. By attaching the imaging device 13 to thebiaxial mirror unit 5, it is possible to acquire an image of thelocation scheduled to be irradiated with the laser light in accordancewith the movement of the biaxial mirror unit 5.

The optical path of the excitation laser device 1 is bent by the mirror8 a at a 90-degree angle and introduced into the excitation lasercondensing unit 10. That is, the excitation laser light output by theexcitation laser device 1 is bent by the mirror 8 a at a 90-degree angleand moves to the excitation laser condensing unit 10. The excitationlaser light output by the excitation laser condensing unit 10 foroutputting excitation laser light is bent by the mirror 8 c at a90-degree angle and moves to the galvano scanner unit 3 so that theexcitation laser condensing unit 10 condenses the laser light on thesurface of the inspection target M.

The optical path of the measurement laser device 2 is introduced intothe measurement laser condensing unit 11. That is, the measurement laserlight output by the measurement laser device 2 moves to the measurementlaser condensing unit 11. The measurement laser condensing unit 11condenses the measurement laser light and outputs the condensedmeasurement laser light to the galvano scanner unit 3.

The galvano scanner unit 3 adjusts optical paths of either or both ofthe excitation laser light and the measurement laser light in anydirection and angle by rotating the galvano scanner mirror 4 a and thegalvano scanner mirror 4 b to an appropriate angle using a motor. Theexcitation laser light and the measurement laser light whose opticalpaths are adjusted in any direction and angle by the galvano scannerunit 3 are output to the biaxial mirror unit 5.

The biaxial mirror unit 5 adjusts the biaxial mirror 6 to set a coarsemovement irradiation position whose setting is difficult in the galvanoscanner unit 3. The excitation laser light and the measurement laserlight output to the biaxial mirror unit 5 are radiated to a scheduledirradiation position of the inspection target M set by the biaxialmirror unit 5.

FIG. 2 is a conceptual diagram of sweeping of the laser-inducedvibration wave measuring system of the first embodiment.

When the inspection target M is irradiated with the excitation laserlight and the measurement laser light, the biaxial mirror unit 5performs a sweep operation in the order of a biaxial mirror irradiationarea 203-1, a biaxial mirror irradiation area 203-2, a biaxial mirrorirradiation area 203-3, and a biaxial mirror irradiation area 203-4according to a preset sweep order SO-1.

When the biaxial mirror unit 5 performs a sweep operation in the biaxialmirror irradiation area 203-1, the galvano scanner unit 3 performs asweep operation in the order of an irradiation area 200-11, anirradiation area 200-12, an irradiation area 200-13, an irradiation area200-14, and an irradiation area 200-15 according to a preset sweep orderSO-11. When the galvano scanner unit 3 performs a sweep operation in theirradiation area 200-11, an excitation laser light irradiation locationand a measurement laser light irradiation location are irradiated withthe excitation laser light and the measurement laser light by rotatingthe galvano scanner mirror 4 a and the galvano scanner mirror 4 b to theappropriate angle using the motor.

Even if the galvano scanner unit 3 performs a sweep operation in theirradiation areas 200-12 to 200-15, it is possible to apply a process ofperforming a sweep operation in the irradiation area 200-11. Even if thebiaxial mirror unit 5 performs a sweep operation in the biaxial mirrorirradiation areas 203-2 to 203-4, it is possible to apply a process ofperforming a sweep operation in the biaxial mirror irradiation area203-1.

In this manner, it is possible to sweep the laser light at any locationof the inspection target M at a high speed by combining the galvanoscanner unit 3 and the biaxial mirror unit 5. As a specific example, inthe case of a tunnel having a radius of 5 m to 10 m, an interval betweenhitting points 200 becomes a preferable range of 10 mm to 300 mm withinan area 203 of 0.1 m×0.1 m to 1 m×1 m, which is a range of onemeasurement operation. Returning to FIG. 1 , the description will becontinued.

The laser-induced vibration wave measuring system 20 adjusts acondensing position of the excitation laser condensing unit 10.Specifically, the laser-induced vibration wave measuring system 20adjusts the condensing position by adjusting a distance between the lens12 a and the lens 12 b mounted on the excitation laser condensing unit10. The laser-induced vibration wave measuring system 20 adjusts adistance between the lens 12 c and the lens 12 d mounted on themeasurement laser condensing unit 11.

Also, the laser-induced vibration wave measuring system 20 sets alocation of the inspection target M to be irradiated with the excitationlaser light and the measurement laser light.

Also, in the laser-induced vibration wave measuring system 20, a soundis generated by irradiating the inspection target M with either or bothof the excitation laser light and the measurement laser light and aninfluence of direct arrival of the generated sound and an influence ofan echo of the sound are reduced.

A process of adjusting the distance between the lens 12 a and the lens12 b mounted on the excitation laser condensing unit 10 and the distancebetween the lens 12 c and the lens 12 d mounted on the measurement lasercondensing unit 11 will be described. Because it is possible tocompensate for a “change in a distance between a laser irradiationportion and a measurement target” according to adjustment of the lasercondensing position by adjusting the distance between the lens 12 a andthe lens 12 b mounted on the excitation laser condensing unit 10 and thedistance between the lens 12 c and the lens 12 d mounted on themeasurement laser condensing unit 11, the accuracy of measurement at thetime of high-speed measurement can be improved.

The distance measurement laser light output by the distance measurementlaser device 9 is bent by the mirror 8 b at a 90-degree angle and movesto the galvano scanner unit 3. The galvano scanner unit 3 includes agalvano scanner mirror 4 a and a galvano scanner mirror 4 b. The galvanoscanner unit 3 adjusts the optical path of the distance measurementlaser light in any direction and angle by rotating the galvano scannermirror 4 a and the galvano scanner mirror 4 b to an appropriate angleusing the motor. The distance measurement laser light whose optical pathhas been adjusted in any direction and angle by the galvano scanner unit3 is output to the biaxial mirror unit 5.

The biaxial mirror unit 5 includes the biaxial mirror 6 and sets acoarse movement irradiation position whose setting is difficult in thegalvano scanner unit 3 by adjusting the biaxial mirror 6. The distancemeasurement laser light output to the biaxial mirror unit 5 is radiatedto the irradiation position of the inspection target M set by thebiaxial mirror unit 5.

Reflected light obtained by reflecting the distance measurement laserlight radiated to the irradiation position of the inspection target Mmoves to the distance measurement laser device 9 via the biaxial mirrorunit 5, the galvano scanner unit 3 and the mirror 8 b and is detected bya light receiving element of the distance measurement laser device 9.The distance measurement laser device 9 derives an irradiation distancebetween the distance measurement laser device 9 and the inspectiontarget M on the basis of the reflected light detected by the lightreceiving element and outputs information representing the derivedirradiation distance (irradiation distance information) to theprocessing unit 100.

The processing unit 100 acquires information representing theirradiation distance output by the distance measurement laser device 9and derives an amount of adjustment of the distance between the lens 12a and the lens 12 b of the excitation laser condensing unit 10 and atime period required for the adjustment on the basis of the acquiredinformation representing the irradiation distance. The processing unit100 adjusts the distance between the lens 12 a and the lens 12 b on thebasis of the derived amount of adjustment. Specifically, the processingunit 100 outputs information representing the derived amount ofadjustment of the distance between the lens 12 a and the lens 12 b tothe excitation laser condensing unit 10. The excitation laser condensingunit 10 acquires information representing the amount of adjustment ofthe distance between the lens 12 a and the lens 12 b output by theprocessing unit 100 and adjusts the distance between the lens 12 a andthe lens 12 b on the basis of the acquired information representing theamount of adjustment of the distance between the lens 12 a and the lens12 b. The adjustment of the distance between the lens 12 a and the lens12 b is performed by moving either or both of the lens 12 a and the lens12 b. By adjusting the distance between the lens 12 a and the lens 12 b,the excitation laser light can be condensed and radiated to theinspection target M.

FIGS. 3A and 3B are diagrams showing an example of a frequency spectrumof induced vibration obtained by the processing unit of thelaser-induced vibration wave measuring system of the first embodiment.In FIGS. 3A and 3B, the horizontal axis represents a frequency of theinduced vibration and the vertical axis represents a normalizedintensity of vibration. The normalized intensity of vibration is anintensity when a peak value before adjustment is 1. FIG. 3A is afrequency spectrum obtained when the distance between the lens 12 a andthe lens 12 b is not adjusted. Also, FIG. 3B is a frequency spectrumobtained when the distance between the lens 12 a and the lens 12 b isadjusted. For example, in FIGS. 3A and 3B, a condensing diameter (FIG.3A) of the excitation laser light in a state in which the distancebetween the lenses 12 a and 12 b is not adjusted is 7.9 mm and acondensing diameter (FIG. 3B) of the excitation laser light in a statein which the distance between the lenses 12 a and 12 b is adjusted is4.4 mm.

According to FIG. 3A, because the condensing diameter of the excitationlaser light is widened when the distance between the lens 12 a and thelens 12 b is not adjusted, an intensity of irradiation per unit area ofthe excitation laser light for exciting the surface vibration of theinspection target M decreases. Thus, the intensity of a signal in thefrequency spectrum decreases.

Frequency spectra of induced vibrations shown in FIGS. 3A and 3B areobtained when excitation is performed in an ablation mode. Also,although the intensity of a signal is reduced by widening the condensingdiameter, it is possible to perform switching to a thermal mode in whichmeasurement is performed only by thermal expansion without damaging thesurface in ablation. In the case of the thermal mode, the condensingdiameter of the excitation laser light becomes about 100 mm. Thus, it ispreferable that the condensing diameter of the excitation laser light be100 μm to 100 mm.

According to FIG. 3B, because the condensing diameter of the excitationlaser light is narrowed when the distance between the lens 12 a and thelens 12 b is adjusted, an intensity of irradiation per unit area of theexcitation laser light for exciting the surface vibration of theinspection target M increases. Thus, the intensity of a signal in thefrequency spectrum is improved. The intensity of irradiation per unitarea is in a preferable range of 10 mJ/cm² to 10 kJ/cm². Returning toFIG. 1 , the description will be continued.

The processing unit 100 acquires information representing theirradiation distance output by the distance measurement laser device 9and derives an amount of adjustment of the distance between the lens 12c and the lens 12 d of the measurement laser condensing unit 11 and atime period required for the adjustment on the basis of the acquiredinformation representing the irradiation distance. The processing unit100 adjusts the distance between the lens 12 c and the lens 12 d on thebasis of the derived amount of adjustment. Specifically, the processingunit 100 outputs information representing the derived amount ofadjustment of the distance between the lens 12 c and the lens 12 d tothe excitation laser condensing unit 10. The excitation laser condensingunit 10 acquires the information representing the amount of adjustmentof the distance between the lens 12 c and the lens 12 d output by theprocessing unit 100 and adjusts the distance between the lens 12 c andthe lens 12 d on the basis of information representing the acquiredamount of adjustment of the distance between the lens 12 c and the lens12 d. The adjustment of the distance between the lens 12 c and the lens12 d is performed by moving either or both of the lens 12 c and the lens12 d. By adjusting the distance between the lens 12 c and the lens 12 d,the measurement laser light can be condensed and radiated to theinspection target M.

When the distance between the lens 12 c and the lens 12 d is notadjusted, the measurement laser system that detects the vibration of thecondensing position will not be able to perform measurement because thecondensing position is not set on the inspection target.

Next, a process of setting a location of the inspection target M to beirradiated with at least one of the excitation laser light, themeasurement laser light, and the distance measurement laser light willbe described. Because it is possible to exclude a “change in ameasurement target surface” by setting the location of the inspectiontarget M to be irradiated with at least one of the excitation laserlight, the measurement laser light, and the distance measurement laserlight, it is possible to exclude one of the causes of the measurementerror when high-speed measurement is performed.

The imaging device 13 images a location of the inspection target Mscheduled to be irradiated with the laser light. The imaging device 13transmits information representing an image of the location of theinspection target M scheduled to be irradiated with at least one of theexcitation laser light, the measurement laser light, and the distancemeasurement laser light obtained through the imaging (hereinafterreferred to as a “scheduled laser irradiation location image”) to theprocessing unit 100. Specifically, the imaging device 13 images theirradiation areas 200-11, . . . , the irradiation area 200-15, and thelike described with reference to FIG. 2 .

The processing unit 100 acquires the information representing thescheduled laser irradiation location image transmitted by the imagingdevice 13 and performs image processing on the acquired informationrepresenting the scheduled laser irradiation location image. Theprocessing unit 100 detects a state of the inspection target M such aswetness, a shape, or an appendage on the basis of the scheduled laserirradiation location image obtained through the image processing. Theprocessing unit 100 selects a scheduled laser irradiation location to beirradiated with either or both of the excitation laser light and themeasurement laser light from a plurality of scheduled laser irradiationlocations on the basis of the state of the inspection target M.

For example, it is preferable to select a scheduled laser irradiationlocation that has no uneven shadow, is flat, has the same wetness asother scheduled laser irradiation locations, and has no appendage on thebasis of the state of the inspection target M. It is preferable to avoida location where there is an appendage, a cracked location (an inside ofa crack), a repaired location, and a marked location as the scheduledlaser irradiation location.

When all selected scheduled laser irradiation locations are connected bya line on the basis of the selected scheduled laser irradiationlocations, the processing unit 100 selects a route having the shortestlength from among routes for radiating laser light represented by theconnected line. Also, when there is a route that passes over theappendage, the processing unit 100 may select the shortest route underthe assumption that the laser light is blocked by a physical shutter sothat the appendage is not irradiated with the laser light. Theprocessing unit 100 sets the selected route as a sweep route and outputsa result of selecting an irradiation location including informationrepresenting the sweep route to the galvano scanner unit 3 and thebiaxial mirror unit 5.

The galvano scanner unit 3 and the biaxial mirror unit 5 sweep at leastone of the excitation laser light, the measurement laser light, and thedistance measurement laser light on the basis of the result of selectingthe irradiation location output by the processing unit 100.

A process of reducing an influence of a sound generated by irradiatingthe inspection target M with at least one of the excitation laser light,the measurement laser light, and the distance measurement laser lightand an influence of an echo of the sound will be described. The soundgenerated by irradiating the inspection target M with the laser lightand the echo of the sound are collectively referred to as reverberationsounds. Because “noise originating from an inspection environment” canbe excluded by reducing the influence of a sound generated byirradiating the inspection target M with at least one of the excitationlaser light, the measurement laser light, and the distance measurementlaser light and the influence of an echo of the sound, it is possible toexclude one of the causes of the measurement error when high-speedmeasurement is performed.

When laser-induced vibration wave measurement is performed in a closedspace such as a tunnel, a sound generated by irradiating the inspectiontarget M with either or both of the excitation laser light and themeasurement laser light may echo and an echo may become noise.

The inspection target M is irradiated with either or both of theexcitation laser light and the measurement laser light at a firsttiming.

The reverberation sound monitor 7 measures an intensity of a soundgenerated when the inspection target M is irradiated with either or bothof the excitation laser light and the measurement laser light at thefirst timing. Here, the sound includes a sound generated when theinspection target M is irradiated with either or both of the excitationlaser light and the measurement laser light, an echo generated when thesound echoes by a tunnel wall or the like, and a reverberation sound.The reverberation sound monitor 7 converts the measured sound into anelectrical signal and outputs an intensity of a sound (hereinafterreferred to as “sound information”) obtained through the conversion intothe electrical signal to the processing unit 100.

The processing unit 100 generates time-series data of an intensity of areverberation sound on the basis of the sound information output by thereverberation sound monitor 7.

The reverberation sound monitor 7 measures an intensity of a soundgenerated when the inspection target is irradiated with either or bothof the excitation laser light and the measurement laser light. Thereverberation sound monitor 7 converts the measured sound into anelectrical signal and outputs sound information obtained through theconversion into the electrical signal to the processing unit 100. Theprocessing unit 100 generates time-series data of an intensity of areverberation sound on the basis of the sound information output by thereverberation sound monitor 7.

Time-series data of the reverberation sound will be described using FIG.7A. S1 is time-series data of a reverberation sound measured when theinspection target is irradiated with either or both of the excitationlaser light and the measuring laser light at a timing of 0 ms. Forexample, a signal observed at 20 ms, 50 ms, 75 ms, or the like in S1 isa reverberation sound. Because the time-series data of the reverberationsound changes according to a measurement environment (for example, thesize and the shape of the tunnel, the distance to the inspection target,or the like), it is desirable to perform measurement each time themeasurement environment changes and output a measurement result to theprocessing unit 100.

The processing unit 100 derives a laser irradiation timing at which theinfluence of the reverberation sound is small and a time period in whichthe vibration of the inspection target M can be measured is longest onthe basis of the time-series data of the reverberation sound. Forexample, in FIG. 7A, laser irradiation and measurement are performedfour times in total at intervals of 20 ms. The time-series data of thereverberation sound generated in x^(th) irradiation is Sx and themeasurement is performed in a time period of Mx immediately after thelaser irradiation. Because the reverberation sound is generated for eachirradiation operation, reverberation sounds (S1 to S(x−1)) of the laserirradiation operations up to (x−1)^(th) irradiation are summed andremains in the measurement time period of Mx. If the peak of thereverberation sound is included in the measurement time period, theaccuracy of measurement decreases. For example, peaks of S1 and S2 areincluded in a measurement time period of M3. The processing unit 100derives a laser irradiation timing at which the influence of areverberation sound of previous irradiation is minimized with respect toeach measurement operation. Specifically, as shown in FIG. 7B, a laserirradiation timing (interval) at which the intensity of time-series dataobtained by summing the reverberation sounds of S1 to S(x−1) isminimized in the measurement time period of Mx is derived. Also, becausetime-series data of a reverberation sound generated in one laserirradiation operation is the same every time when the measurementenvironment does not change, the same time-series data may be used forS1 to Sx if the measurement environment does not change. The processingunit 100 outputs information representing the derived timing to eitheror both of the excitation laser device 1 and the measurement laserdevice 2. Because it is not preferable to change a timing during ahigh-speed sweep operation by the galvano scanner unit 3, it ispreferable that the processing unit 100 change the timing when ahigh-speed sweep range is changed by the biaxial mirror unit 5, i.e.,while the high-speed sweep unit is stopped.

Either or both of the excitation laser device 1 and the measurementlaser device 2 output either or both of the excitation laser light andthe measurement laser light on the basis of the information representingthe timing output by the processing unit 100.

The processing unit 100 constituting the laser-induced vibration wavemeasuring system 20 will be described in detail.

(Processing Unit 100)

FIG. 4 is a block diagram showing an example of a processing unit of thelaser induced vibration wave measuring system of the first embodiment.

The processing unit 100 is implemented by a device such as a personalcomputer, a server, a smartphone, a tablet computer, or an industrialcomputer.

The processing unit 100 includes, for example, a communicating portion110, an information processing portion 120, a display portion 130, and astoring portion 140.

The communicating portion 110 is implemented by a communication module.The communicating portion 110 communicates with other external devicesvia a network. The communicating portion 110 may perform communicationusing a communication scheme of a wireless local area network (LAN), awired LAN, Bluetooth (registered trademark), Long Term Evolution (LTE)(registered trademark), or the like.

The communicating portion 110 receives information representing anirradiation distance output by the distance measurement laser device 9and outputs the received information representing the irradiationdistance to the information processing portion 120. The communicatingportion 110 acquires control information including informationrepresenting an amount of adjustment of a condensing position such as anamount of adjustment of a distance between the lens 12 a and the lens 12b output by the information processing portion 120 with respect to theinformation representing the irradiation distance and outputs theacquired control information including the information representing theamount of adjustment of the condensing position to the excitation lasercondensing unit 10.

Also, the communicating portion 110 acquires control informationincluding information representing an amount of adjustment of acondensing position such as an amount of adjustment of a distancebetween the lens 12 c and the lens 12 d output by the informationprocessing portion 120 with respect to information representing theirradiation distance and outputs the acquired control information to themeasurement laser condensing unit 11.

The communicating portion 110 receives information representing thescheduled laser irradiation location image output by the imaging device13 and outputs the received information representing the scheduled laserirradiation location image to the information processing portion 120.The communicating portion 110 acquires control information including aresult of selecting the irradiation location output by the informationprocessing portion 120 with respect to the information representing thelaser irradiation location image and transmits the acquired controlinformation to the galvano scanner unit 3 and the biaxial mirror unit 5.

The communicating portion 110 outputs sound information output by thereverberation sound monitor 7 to the information processing portion 120.The communicating portion 110 acquires control information includinginformation representing a timing output by the information processingportion 120 with respect to sound information and outputs the acquiredcontrol information to either or both of the excitation laser device 1and the measurement laser device 2.

The communicating portion 110 outputs vibration data output by themeasurement laser device 2 to the information processing portion 120.

For example, the display portion 130 includes a liquid crystal displayor the like, and displays a result of inspecting the faultlessness of aportion of the inspection target M irradiated with the excitation laserlight.

For example, the storing portion 140 is implemented by a random accessmemory (RAM), a read only memory (ROM), a hard disk drive (HDD), a flashmemory, a hybrid storage device in which the RAM, the ROM, and the HDDare combined, or the like. Instead of a case in which the storingportion 140 is provided as a part of the processing unit 100, a part orall of the storing portion 140 may be implemented by an external devicecapable of being accessed by a processor of the processing unit 100 viaa network such as a network attached storage (NAS) or an externalstorage server. The storing portion 140 stores a program 142 to beexecuted by the information processing portion 120, an inter-lensdistance table 144, and a surrounding measurement data database (DB)146.

The inter-lens distance table 144 is information in the form of a tablein which information representing an irradiation distance, a focalposition adjusted by the excitation laser condensing unit 10 foraligning a focus at the irradiation distance, a focal position adjustedby the measurement laser condensing unit 11, and a time period requiredfor adjusting the focal position are associated. In the presentembodiment, description will continue with a case in which the focalposition is adjusted in the measurement laser condensing unit 11 byadjusting an inter-lens distance between the lenses 12 a and 12 b andthe focal position is adjusted in the measurement laser condensing unit11 by adjusting an inter-lens distance between the lenses 12 c and 12 d.

The surrounding measurement data DB 146 stores vibration data measuredin the past.

For example, the information processing portion 120 is a functionalportion (hereinafter referred to as a software function portion)implemented by a processor such as a central processing unit (CPU)executing the program 142 stored in the storing portion 140. Also, allor a part of the information processing portion 120 may be implementedby hardware such as a large-scale integration (LSI) circuit, anapplication specific integrated circuit (ASIC), or a field-programmablegate array (FPGA) or may be implemented by a combination of the softwarefunction portion and the hardware.

The information processing portion 120 includes, for example, aninformation acquiring portion 122, a measuring portion 124, and ananalyzing portion 126.

The information acquiring portion 122 includes an irradiation distancedata acquiring portion 122 a, an irradiation location data acquiringportion 122 b, a reverberation sound data acquiring portion 122 c, and avibration data acquiring portion 122 d.

The irradiation distance data acquiring portion 122 a acquiresinformation representing the irradiation distance output by thecommunicating portion 110 and outputs the acquired informationrepresenting the irradiation distance to the measuring portion 124.

The irradiation location data acquiring portion 122 b acquiresinformation representing a scheduled laser irradiation location imageoutput by the communicating portion 110 and outputs the acquiredinformation representing the scheduled laser irradiation location imageto the measuring portion 124.

The reverberation sound data acquiring portion 122 c acquires soundinformation output by the communicating portion 110 and outputs theacquired sound information to the measuring portion 124.

The vibration data acquiring portion 122 d acquires vibration dataoutput by the communicating portion 110 and outputs the acquiredvibration data to the analyzing portion 126.

(Measuring Portion 124)

The measuring portion 124 includes a condensing position derivingportion 124 a, an irradiation location analyzing portion 124 b, areverberation sound analyzing portion 124 c, and a timing derivingportion 124 d.

The condensing position deriving portion 124 a acquires informationrepresenting the irradiation distance output by the irradiation distancedata acquiring portion 122 a and derives an amount of adjustment of thedistance between the lens 12 a and the lens 12 b, an amount ofadjustment of the distance between the lens 12 c and the lens 12 d, anda time period required for adjusting the distance between the lenses onthe basis of the acquired information representing the irradiationdistance.

Specifically, the condensing position deriving portion 124 a acquiresinformation representing a current distance between the lens 12 a andthe lens 12 b from the excitation laser condensing unit 10 and storesthe acquired information representing the current distance between thelens 12 a and the lens 12 b. It is preferable that the condensingposition deriving portion 124 a acquire the information representing thecurrent distance between the lens 12 a and the lens 12 b during ahigh-speed sweep operation of the galvano scanner unit 3, in otherwords, at a timing when the galvano scanner unit 3 stops. Also, thecondensing position deriving portion 124 a acquires informationrepresenting the current distance between the lens 12 c and the lens 12d from the measurement laser condensing unit 11 and stores the acquiredinformation representing the current distance between the lens 12 c andthe lens 12 d. It is preferable that the condensing position derivingportion 124 a acquire information representing the current distancebetween the lens 12 c and the lens 12 d during a high-speed sweepoperation of the galvano scanner unit 3, in other words, at the timingwhen the galvano scanner unit 3 stops.

When the information representing the irradiation distance has beenacquired, the condensing position deriving portion 124 a acquires aninter-lens distance between the lenses 12 a and 12 b and a time periodrequired for adjusting the inter-lens distance stored in associationwith the acquired information representing the irradiation distance withreference to the inter-lens distance table 144. The condensing positionderiving portion 124 a derives a difference between the acquiredinter-lens distance between the lens 12 a and the lens 12 b and thecurrent distance between the lens 12 a and the lens 12 b, therebyderiving an amount of adjustment of the distance between the lens 12 aand the lens 12 b. The condensing position deriving portion 124 aoutputs information representing the derived amount of adjustment of thedistance between the lenses 12 a and 12 b and time information requiredfor adjusting the inter-lens distance to the timing deriving portion 124d.

Also, when the information representing the irradiation distance hasbeen acquired, the condensing position deriving portion 124 a acquiresan inter-lens distance between the lens 12 c and the lens 12 d and atime period required for adjusting the inter-lens distance stored inassociation with the acquired information representing the irradiationdistance with reference to the inter-lens distance table 144. Thecondensing position deriving portion 124 a derives a difference betweenthe acquired inter-lens distance between the lens 12 c and the lens 12 dand the current distance between the lens 12 c and the lens 12 d,thereby deriving an amount of adjustment of the distance between thelens 12 c and the lens 12 d. The condensing position deriving portion124 a outputs information representing the derived amount of adjustmentof the distance between the lens 12 c and the lens 12 d and timeinformation required for adjusting the inter-lens distance to the timingderiving portion 124 d.

The irradiation location analyzing portion 124 b acquires theinformation representing the scheduled laser irradiation location imageoutput by the irradiation location data acquiring portion 122 b andperforms image processing on the acquired information representing thescheduled laser irradiation location image. The irradiation locationanalyzing portion 124 b detects a state of the inspection target M suchas wetness, a shape, or an appendage on the basis of the scheduled laserirradiation location image obtained through the image processing. Theirradiation location analyzing portion 124 b selects a scheduled laserirradiation location that has no uneven shadow, is flat, has the samewetness as other scheduled laser irradiation locations, and has noappendage on the basis of the state of the inspection target M.

For example, when all selected scheduled laser irradiation locations areconnected by a line on the basis of the selected scheduled laserirradiation locations, the irradiation location analyzing portion 124 bselects a route having the shortest length from among routes forradiating laser light represented by the connected line. Also, whenthere is a route that passes over the appendage, the irradiationlocation analyzing portion 124 b may select the shortest route under theassumption that the laser light is blocked by the physical shutter sothat the appendage is not irradiated with the laser light. Theirradiation location analyzing portion 124 b sets the selected route asa sweep route and outputs a result of selecting an irradiation locationincluding information representing the sweep route to the timingderiving portion 124 d. The sweep operation can be performed at thehighest speed using a route having the shortest length among routes ofall the selected scheduled laser irradiation locations connected by aline as the sweep route.

FIG. 5 is a diagram showing an example of a scheduled laser irradiationlocation image. In an example of the scheduled laser irradiationlocation image shown in FIG. 5 , a total of 25 scheduled laser(excitation laser) irradiation locations formed by five verticallocations and five horizontal locations are shown. Further, a cable C isshown in an example of the scheduled laser irradiation location image.

The irradiation location analyzing portion 124 b determines that laserirradiation is not possible because the cable C is present on eachscheduled laser irradiation location with respect to scheduled laserirradiation locations where (X, Y) is (2, 4), (3, 3), and (4, 3) amongthe 25 scheduled laser irradiation locations on the basis of thescheduled laser irradiation location image. The irradiation locationanalyzing portion 124 b selects scheduled laser irradiation locationsother than the scheduled laser irradiation locations where (X, Y) is (2,4), (3, 3), and (4, 3) and selects a route having the shortest lengthamong routes indicated by a line connecting all the selected scheduledlaser irradiation locations. The irradiation location analyzing portion124 b sets the selected route as the sweep route and outputs a result ofselecting an irradiation location including information representing thesweep route to the timing deriving portion 124 d. Returning to FIG. 4 ,the description will be continued.

The reverberation sound analyzing portion 124 c derives a measurementcondition on the basis of sound information output by the reverberationsound data acquiring portion 122 c.

FIG. 6 is a diagram showing an example (part 1) of sound information. InFIG. 6 , the horizontal axis represents time [ms] and the vertical axisrepresents an intensity of a sound (arb. unit). This sound informationis an inspection speed of 50 Hz, i.e., measurement is performed 50 timesper second. In the example shown in FIG. 6 , the inspection target M isirradiated with the excitation laser light every 20 ms. Thus, a sound isgenerated by irradiating the inspection target M with the excitationlaser light every 20 ms and a plurality of peaks L of the sound aredetected. Furthermore, after 8 ms of each of the plurality of peaks L, apeak N and an attenuation waveform due to a reverberation sound of thesound generated by irradiating the inspection target M with theexcitation laser light are detected for several milliseconds. Becausethe plurality of peaks N and each of the attenuation waveforms arenoise, the accuracy of measurement deteriorates if the time when each ofthe plurality of peaks N is detected is included in the measurementtime. This will be specifically described.

FIGS. 7A and 7B are diagrams showing an example (part 2) of the soundinformation.

FIGS. 8A and 8B are diagrams showing an example (part 3) of the soundinformation.

FIG. 7A shows a reverberation sound generated by the excitation laserlight that has been sequentially radiated when the inspection target Mis sequentially irradiated with the excitation laser light at 20 msintervals (50 Hz). Because a measurement environment in FIG. 7A isdifferent from that in FIG. 6 , a timing at which noise due to thereverberation sound occurs is different in FIG. 7A. Also, the waveformof the reverberation sound is observed as a single peak in FIG. 6 and isobserved as an attenuation waveform in FIG. 7A, which is a difference inirradiation energy. An afterimage sound is a periodic sound signal whichis received outside the irradiation time of the excitation laser light.

FIG. 7B shows a reverberation sound generated by the excitation laserlight that has been sequentially radiated when the inspection target Mhas been sequentially irradiated with the excitation laser light at 30ms intervals (33 Hz).

In FIGS. 7A and 7B, waveforms S1 to S4 are waveforms representingreverberation sounds generated by sequentially irradiating theinspection target M with the excitation laser light. Time periods M1 toM4 are time periods in which vibrations generated in the inspectiontarget M are measured with respect to the sequentially radiated laserlight. An upward arrow indicates an irradiation timing of the excitationlaser light.

FIG. 8A shows a reverberation sound generated by the excitation laserlight that has been sequentially radiated when the inspection target Mhas been sequentially irradiated with the excitation laser light at 25ms intervals (40 Hz).

FIG. 8B shows a reverberation sound generated by the excitation laserlight that has been sequentially radiated when the inspection target Mhas been sequentially irradiated with the excitation laser light at 40ms intervals (25 Hz).

In FIGS. 8A and 8B, waveforms S1 to S4 are waveforms representingreverberation sounds generated by sequentially irradiating theinspection target M with the excitation laser light. Time periods M1 toM4 are time periods in which vibrations generated in the inspectiontarget M are measured with respect to the sequentially radiated laserlight. An upward arrow indicates an irradiation timing of the excitationlaser light.

According to FIGS. 7A, 7B, 8A, and 8B, the reverberation sound (noise)due to the previous irradiation is included in a measurement result inthe time period when second and subsequent measurements (measurement)represented in the time periods M2 to M4 are (is) performed. That is,the vibration measured in a time period of Mn (n is an integer of n>1)includes a waveform obtained by summing all the waveforms S1 to Sn.Specifically, in the case of FIG. 7A, in the vibration measured in thetime period M4, waveforms S1 to S4 are included in the measurementresult. Among the waveforms S1 to S4, the waveforms S2 and S3 have aparticularly large amplitude and an increased number of noisecomponents. However, in the case of FIG. 7B, in the vibration measuredin the time period M4, the waveforms S1 to S4 are included in themeasurement result, but any of the waveforms S1 to S4 has a smallamplitude and a decreased number of noise components.

In the case of FIG. 8A, in the vibration measured in the time period M4,waveforms S1 to S4 are included in the measurement result. Among thewaveforms S1 to S4, the waveform S2 has a particularly large amplitudeand an increased number of noise components. In the case of FIG. 8B, inthe vibration measured in the time period M4, the waveforms S1 to S4 areincluded in the measurement result. Among the waveforms S1 to S4, thewaveform S3 has a particularly large amplitude and an increased numberof noise components.

A time waveform of the reverberation sound varies with an irradiationenvironment such as a size of a tunnel, a road (a road surface), a pierfloor plate, a concrete wall, and a position of the reverberation soundmonitor 7. The reverberation sound analyzing portion 124 c derives ameasurement condition such as the number of repetitions (a timing) forminimizing the noise component on the basis of the sound informationacquired by the reverberation sound monitor 7 before the vibration ismeasured. For example, according to FIG. 6 , the reverberation soundanalyzing portion 124 c derives a timing at which the sound becomes asilent sound having a signal amount which is less than or equal to abouttwice a signal amount of a non-irradiation time (a background) afterirradiation with the excitation laser and a time period of the silentsound can be secured for about 10 ms. For example, when thelaser-induced vibration wave measuring system 20 is mounted on a movingbody or the like to be described below, the timing is derived in thestationary state.

When the reverberation sounds shown in FIGS. 7A, 7B, 8A, and 8B havebeen obtained, the reverberation sound analyzing portion 124 c derives a30 ms interval (33 Hz) as the measurement condition and outputs thederived measurement condition to the timing deriving portion 124 d andthe analyzing portion 126. In this manner, it is possible to performmeasurement in which an influence of a noise component generated by theexcitation laser light that has been sequentially radiated is reduced byoptimizing the number of repetitions (the timing). Returning to FIG. 4 ,the description will be continued.

The timing deriving portion 124 d acquires information representing anamount of adjustment of a distance between the lens 12 a and the lens 12b output by the condensing position deriving portion 124 a and timeinformation required for adjusting an inter-lens distance and outputscontrol information including the acquired information representing theamount of adjustment of the distance between the lens 12 a and the lens12 b to the communicating portion 110 at a predetermined timing on thebasis of the acquired time information required for adjusting theinter-lens distance.

The timing deriving portion 124 d acquires information representing anamount of adjustment of a distance between the lens 12 c and the lens 12d output by the condensing position deriving portion 124 a and timeinformation required for adjusting an inter-lens distance and outputscontrol information including the acquired information representing theamount of adjustment of the distance between the lens 12 c and the lens12 d to the communicating portion 110 at a predetermined timing on thebasis of the acquired time information required for adjusting theinter-lens distance.

The timing deriving portion 124 d acquires information representing aresult of selecting an irradiation location output by the irradiationlocation analyzing portion 124 b and outputs control informationincluding the acquired information representing the result of selectingthe irradiation location to the communicating portion 110 at apredetermined timing.

The timing deriving portion 124 d acquires information representing ameasurement condition output by the reverberation sound analyzingportion 124 c and outputs control information including the acquiredmeasurement condition to the communicating portion 110 at apredetermined timing.

(Analyzing Portion 126)

The analyzing portion 126 includes a data processing portion 126 a and adetermining portion 126 b.

The data processing portion 126 a acquires a measurement conditionoutput by the timing deriving portion 124 d and vibration data output bythe vibration data acquiring portion 122 d and processes the acquiredvibration data on the basis of the acquired measurement condition. Thedata processing portion 126 a acquires data of a set measurement timeafter removing data of a certain time. Specifically, for example, whenthe measurement time is set to 10 ms, the data processing portion 126 aacquires data of irradiation during a period from 10 ms to 20 ms whendata of 10 ms has been removed.

Here, when the same location of the inspection target M is measured, thevibration data may be vibration data obtained in a single operation ofradiating excitation laser light or vibration data obtained in aplurality of operations of radiating excitation laser light. In thisregard, when vibration data obtained in a plurality of operations ofradiating excitation laser light is used, the data processing portion126 a may average or integrate the vibration data output by thevibration data acquiring portion 122 d.

The data processing portion 126 a extracts data of time periods M1, M2,and the like in which measurement is performed from the vibration dataon the basis of the measurement condition output by the timing derivingportion 124 d. Also, the data processing portion 126 a removes areduction amount arbitrarily determined from the maximum amount ofdisplacement of vibration generated by the excitation laser from theextracted data of the time periods M1, M2, and the like. Here, thereduction amount is, for example, 1/10, 1/100, or the like, and is, forexample, data for a predetermined time period such as a period of 0.5 msto 10 ms after the irradiation with the excitation laser light. Becauseit is possible to reduce an influence of noise generated immediatelyafter irradiation with the excitation laser light by removing areduction amount arbitrarily determined from the maximum amount ofdisplacement of vibration generated by the excitation laser afterirradiation with the excitation laser light, the accuracy of measurementcan be improved.

FIGS. 9A and 9B are diagrams showing effects of noise removal of thelaser-induced vibration wave measuring system of the first embodiment.FIGS. 9A and 9B show frequency spectra obtained by performing a fastFourier transform on vibration data. FIG. 9A shows a case in which noiseis not removed from the vibration data and FIG. 9B shows a case in whichnoise is removed from the vibration data.

According to FIG. 9A, noise due to a sound generated by the irradiationwith the excitation laser light has a large influence and white noisewhich appears to be raised as a whole is generated. On the other hand,according to FIG. 9B, white noise is reduced and a fine peak isobserved.

Also, the data processing portion 126 a determines whether or not theacquired vibration data includes noise generated by an unexpectedmeasurement failure. In the laser-induced vibration wave measurement,the vibration generated in the inspection target M is strongestimmediately after the irradiation with the excitation laser light andthen decreases exponentially with the passage of time. Using anexponential function as an evaluation function, the data processingportion 126 a algorithmically determines that vibration data for whichits trend and a correlation coefficient of a certain level or highercannot be obtained includes noise caused by an unexpected measurementfailure.

FIG. 10 is a diagram showing an example of noise removal of thelaser-induced vibration wave measuring system of the first embodiment.In FIG. 10 , (a) is a normal signal (an attenuation waveform) and (b) isnoise caused by an unexpected measurement failure. The data processingportion 126 a derives a coefficient of a correlation with the waveformshown in (b) using the attenuation waveform shown in (a) as anevaluation function. When the correlation coefficient is greater than orequal to a correlation coefficient threshold value, the data processingportion 126 a determines that the waveform shown in (b) is a signal.Also, when the correlation coefficient is less than the correlationcoefficient threshold value, the data processing portion 126 adetermines that the waveform shown in (b) is not a signal but is noisecaused by an unexpected measurement failure. The data processing portion126 a determines that the data determined to include the noise caused bythe unexpected measurement failure is invalid data and removes theinvalid data. Returning to FIG. 4 , the description will be continued.

The data processing portion 126 a acquires valid data obtained byremoving the invalid data.

Here, when the acquired valid data is data obtained by irradiating thesame location of the inspection target M with excitation laser light aplurality of times, the data processing portion 126 a removes noiseunexpectedly generated by irradiating the same location of theinspection target M with excitation laser light a plurality of timesfrom the valid data. Specifically, because the number of times thatnoise unexpectedly generated by irradiating the same location withexcitation laser light a plurality of times is mixed in the vibrationdata is less than the total number of times of irradiation, the dataprocessing portion 126 a removes data including noise unexpectedlygenerated by irradiating the same location with excitation laser light aplurality of times by extracting a predetermined number of waveformsfrom the largest coefficient of a correlation with a waveform obtainedby performing a time average operation on the vibration data.

The data processing portion 126 a may remove either or both of noisecaused by the unexpected measurement failure and the unexpectedlygenerated noise.

FIG. 11 is a diagram showing an example of vibration data acquired bythe laser-induced vibration wave measuring system of the firstembodiment. FIG. 11 shows vibration data for 16 sec when the samelocation of the inspection target M is measured 160 times at aninspection speed of 10 Hz, the horizontal axis represents time (sec),and the vertical axis represents an intensity of vibration (arb. unit).When a fast Fourier transform (FFT) is performed on an average of 160data items after measurement is divided into 160 measurement operations,a frequency spectrum similar to that of FIG. 9B is obtained.

According to FIG. 11 , in a series of band-shaped signals with anintensity of vibration of −0.001 to 0.001, a peak due to unexpectedlygenerated noise appears in addition to a periodic peak that occurs whenexcitation laser light is radiated every 100 ms. Specifically, N in FIG.11 is a location of a signal in which unexpected noise has beengenerated. When unexpected noise has been generated, a black bandindicated by a standard swells. In FIG. 11 , thin lines with equalintervals are white noise.

FIG. 12 is a diagram showing an effect of the laser-induced vibrationwave measuring system of the first embodiment removing unexpectedlygenerated noise. FIG. 12 shows a frequency spectrum obtained byperforming an FFT after unexpectedly generated noise is removed. Asharper frequency spectrum is obtained as compared with the frequencyspectrum obtained by performing an FFT (the lower diagram of FIG. 9 )without removing the unexpectedly generated noise. The data processingportion 126 a outputs information representing the frequency spectrum tothe determining portion 126 b. The data processing portion 126 a storesthe acquired vibration data, the data obtained in the noise removalprocess, and the information representing the frequency spectrum in thesurrounding measurement data DB 146 of the storing portion 140.Returning to FIG. 4 , the description will be continued.

The determining portion 126 b inspects the faultlessness of a portion ofthe inspection target M irradiated with the excitation laser light onthe basis of the frequency spectrum output by the data processingportion 126 a. Specifically, the determining portion 126 b detects thepresence or absence of an internal defect such as a cavity or apossibility that an internal defect will occur.

Also, the determining portion 126 b inspects the faultlessness of aportion of the inspection target M irradiated with excitation laserlight using a frequency spectrum obtained by irradiating the inspectiontarget M with the excitation laser light and a frequency spectrum storedin the surrounding measurement data DB 146 of the storing portion 140.Specifically, the determining portion 126 b detects the presence orabsence of an internal defect such as a cavity or a possibility that aninternal defect will occur. The determining portion 126 b may applymachine learning to inspect the faultlessness of the portion of theinspection target M irradiated with the excitation laser light. Thedetermining portion 126 b may use the frequency spectrum obtained whenthe excitation laser light is not radiated in a case in which thefaultlessness of the portion of the inspection target M irradiated withthe excitation laser light is inspected.

FIGS. 13A and 13B are diagrams showing an example of a frequencyspectrum determined by the laser-induced vibration wave measuring system20 of the first embodiment. FIG. 13A is a frequency spectrum obtainedwhen the inspection target M is irradiated with the excitation laserlight. FIG. 13B is a frequency spectrum obtained when the inspectiontarget M is not irradiated with the excitation laser light. That is,FIG. 13B shows background data. According to FIG. 13B, even if theinspection target M is not irradiated with the excitation laser light,peaks of natural vibration are observed near 2.5 KHz and 5.5 KHz.According to FIG. 13A, it can be seen that the peak of the naturalvibration increases when the inspection target M is irradiated with theexcitation laser light. The determining portion 126 b causes backgrounddata to be included in the frequency spectrum stored in the surroundingmeasurement data DB 146 of the storing portion 140. The determiningportion 126 b may automatically generate an accurate determinationcriterion by applying information that affects determination of naturalvibration such as background data or the like. The determining portion126 b displays information representing a result of inspecting thefaultlessness of the portion of the inspection target M irradiated withthe excitation laser light on the display portion 130.

(Operation of Laser-Induced Vibration Wave Measuring System 20 (Part 1))

FIG. 14 is a sequence chart showing an example (part 1) of the operationof the laser-induced vibration wave measuring system of the firstembodiment. FIG. 14 shows a process of adjusting a distance between thelens 12 a and the lens 12 b and a distance between the lens 12 c and thelens 12 d of the measurement laser condensing unit 11 as an example inwhich a condensing position of the excitation laser condensing unit 10is adjusted.

(Step S101)

The distance measurement laser device 9 outputs distance measurementlaser light.

(Step S102)

The distance measurement laser device 9 derives an irradiation distancebetween the distance measurement laser light and the inspection target Mon the basis of reflected light obtained by reflecting the outputdistance measurement laser light on the inspection target M.

(Step S103)

The distance measurement laser device 9 transmits informationrepresenting the derived irradiation distance (irradiation distanceinformation) to the processing unit 100.

(Step S104)

The communicating portion 110 of the processing unit 100 receives theirradiation distance information transmitted by the distance measurementlaser device 9 and outputs the received irradiation distance informationto the information acquiring portion 122. The irradiation distance dataacquiring portion 122 a of the information acquiring portion 122acquires the irradiation distance information output by thecommunicating portion 110 and outputs the acquired irradiation distanceinformation to the measuring portion 124. The condensing positionderiving portion 124 a of the measuring portion 124 acquires theirradiation distance information output by the irradiation distance dataacquiring portion 122 a and acquires an inter-lens distance between thelens 12 a and the lens 12 b associated with the acquired irradiationdistance information from the inter-lens distance table 144 stored inthe storing portion 140.

(Step S105)

The condensing position deriving portion 124 a derives an amount ofadjustment of the distance between the lens 12 a and the lens 12 b byderiving a difference between the acquired inter-lens distance betweenthe lens 12 a and the lens 12 b and a current distance between the lens12 a and the lens 12 b. The condensing position deriving portion 124 aoutputs information representing the derived amount of adjustment of thedistance between the lens 12 a and the lens 12 b to the timing derivingportion 124 d.

(Step S106)

The timing deriving portion 124 d acquires the information representingthe amount of adjustment of the distance between the lens 12 a and thelens 12 b output by the condensing position deriving portion 124 a,creates control information including the acquired informationrepresenting the amount of adjustment of the distance between the lens12 a and the lens 12 b, and outputs the created control information tothe communicating portion 110. The communicating portion 110 transmitsthe control information output by the timing deriving portion 124 d tothe excitation laser condensing unit 10.

(Step S107)

The excitation laser condensing unit 10 receives the control informationtransmitted by the processing unit 100. The excitation laser condensingunit 10 adjusts the distance between the lens 12 a and the lens 12 b onthe basis of the information representing the amount of adjustment ofthe distance between the lens 12 a and the lens 12 b included in thereceived control information.

(Step S108)

The communicating portion 110 of the processing unit 100 receives theirradiation distance information transmitted by the distance measurementlaser device 9, and outputs the received irradiation distanceinformation to the information acquiring portion 122. The irradiationdistance data acquiring portion 122 a of the information acquiringportion 122 acquires the irradiation distance information output by thecommunicating portion 110 and outputs the acquired irradiation distanceinformation to the measuring portion 124. The condensing positionderiving portion 124 a of the measuring portion 124 acquires theirradiation distance information output by the irradiation distance dataacquiring portion 122 a and acquires an inter-lens distance between thelens 12 c and the lens 12 d associated with the acquired irradiationdistance information from the inter-lens distance table 144 stored inthe storing portion 140.

(Step S109)

The condensing position deriving portion 124 a derives an amount ofadjustment of the distance between the lens 12 c and the lens 12 d byderiving a difference between the acquired inter-lens distance betweenthe lens 12 c and the lens 12 d and a current distance between the lens12 c and the lens 12 d. The condensing position deriving portion 124 aoutputs information representing the derived amount of adjustment of thedistance between the lens 12 c and the lens 12 d to the timing derivingportion 124 d.

(Step S110)

The timing deriving portion 124 d acquires the information representingthe amount of adjustment of the distance between the lens 12 c and thelens 12 d output by the condensing position deriving portion 124 a,creates control information including the acquired informationrepresenting the amount of adjustment of the distance between the lens12 c and the lens 12 d, and outputs the created control information tothe communicating portion 110. The communicating portion 110 transmitsthe control information output by the timing deriving portion 124 d tothe measurement laser condensing unit 11.

(Step S111)

The measurement laser condensing unit 11 receives the controlinformation transmitted by the processing unit 100. The measurementlaser condensing unit 11 adjusts the distance between the lens 12 c andthe lens 12 d on the basis of the information representing the amount ofadjustment of the distance between the lens 12 c and the lens 12 dincluded in the received control information.

In the sequence chart shown in FIG. 14 , a set of steps S104 to S107 anda set of steps S108 to S111 may interchange. Also, step S108 may beperformed after step S104 or step S108 may be performed after step S105.

(Operation of Laser-Induced Vibration Wave Measuring System 20 (Part 2))

FIG. 15 is a sequence chart showing an example (part 2) of the operationof the laser-induced vibration wave measuring system of the firstembodiment. FIG. 15 shows a process in which the galvano scanner unit 3and the biaxial mirror unit 5 control an irradiation location of theinspection target M.

(Step S201)

The imaging device 13 images a location of the inspection target Mscheduled to be irradiated with the laser light.

(Step S202)

The imaging device 13 transmits information representing a scheduledlaser irradiation location image of the inspection target M obtainedthrough the imaging to the processing unit 100.

(Step S203)

The communicating portion 110 of the processing unit 100 receives theinformation representing the scheduled laser irradiation location imageof the inspection target M transmitted by the imaging device 13 andoutputs the received information representing the scheduled laserirradiation location image of the inspection target M to the informationacquiring portion 122. The irradiation location data acquiring portion122 b of the information acquiring portion 122 acquires the informationrepresenting the scheduled laser irradiation location image of theinspection target M output by the communicating portion 110 and outputsthe acquired information representing the scheduled laser irradiationlocation image of the inspection target M to the measuring portion 124.The irradiation location analyzing portion 124 b of the measuringportion 124 acquires the information representing the scheduled laserirradiation location image of the inspection target M output by theirradiation location data acquiring portion 122 b and performs imageprocessing on the acquired information representing the scheduled laserirradiation location image of the inspection target M.

(Step S204)

The irradiation location analyzing portion 124 b of the processing unit100 detects a state of the inspection target M such as wetness, a shape,and an appendage on the basis of the scheduled laser irradiationlocation image obtained through the image processing.

(Step S205)

The irradiation location analyzing portion 124 b of the processing unit100 selects a scheduled laser irradiation location to be irradiated withat least one of excitation laser light, measurement laser light, anddistance measurement laser light from a plurality of scheduled laserirradiation locations on the basis of the state of the inspection targetM.

(Step S206)

For example, when all selected scheduled laser irradiation locations areconnected by a line on the basis of the selected scheduled laserirradiation locations, the irradiation location analyzing portion 124 bof the processing unit 100 selects a route having the shortest lengthfrom among routes indicated by the connected line. Also, when there is aroute that passes over the appendage, the irradiation location analyzingportion 124 b may select the shortest route under the assumption thatthe laser light is blocked by the physical shutter so that the appendageis not irradiated with the laser light. The processing unit 100 sets theselected route as a sweep route and outputs a result of selecting anirradiation location including information representing the sweep routeto the timing deriving portion 124 d.

(Step S207)

The timing deriving portion 124 d acquires the result of selecting theirradiation location output from the irradiation location analyzingportion 124 b, creates control information including the acquired resultof selecting the irradiation location, and outputs the created controlinformation to the communicating portion 110. The communicating portion110 transmits the control information output by the timing derivingportion 124 d to the galvano scanner unit 3 and the biaxial mirror unit5.

(Step S208)

The galvano scanner unit 3 acquires the control information transmittedby the processing unit 100 and adjusts an optical path of at least oneof the excitation laser light, the measurement laser light, and thedistance measurement laser light on the basis of the result of selectingthe irradiation location included in the acquired control information.

(Step S209)

The biaxial mirror unit 5 acquires the control information transmittedby the processing unit 100 and adjusts an optical path of at least oneof the excitation laser light, the measurement laser light, and thedistance measurement laser light on the basis of the result of selectingthe irradiation location included in the acquired control information.

(Operation of Laser-Induced Vibration Wave Measuring System 20 (Part 3))

FIG. 16 is a sequence chart showing an example (part 3) of the operationof the laser-induced vibration wave measuring system of the firstembodiment. FIG. 16 shows a process of controlling an output timing ofexcitation laser light. In FIG. 16 , a case in which the timing at whichthe excitation laser light is output is derived on the basis of anintensity of a sound generated by irradiating the inspection target Mwith the excitation laser light will be described as an example.

(Step S301)

The reverberation sound analyzing portion 124 c of the processing unit100 creates excitation laser light irradiation information that isinformation for causing the excitation laser device 1 to radiate theexcitation laser light and outputs the created excitation laser lightirradiation information to the communicating portion 110. Thecommunicating portion 110 acquires the excitation laser lightirradiation information output by the reverberation sound analyzingportion 124 c and transmits the acquired excitation laser lightirradiation information to the excitation laser device 1. The excitationlaser light irradiation information includes information representing atiming at which the excitation laser light is output. Specifically, theexcitation laser light irradiation information includes a first timing,a second timing, . . . , an i^(th) timing as the timing at which theexcitation laser light is output.

(Step S302)

The excitation laser device 1 outputs the excitation laser lightaccording to the excitation laser light irradiation informationtransmitted by the processing unit 100. The inspection target M isirradiated with the excitation laser light output by the excitationlaser device 1.

(Step S303)

The reverberation sound monitor 7 measures a sound generated when theinspection target M is irradiated with the excitation laser light ateach of the first timing, the second timing, . . . , the i^(th) timing.The reverberation sound monitor 7 converts the measured sound into anelectrical signal and acquires sound information obtained through theconversion into the electrical signal.

(Step S304)

The reverberation sound monitor 7 transmits the acquired soundinformation to the processing unit 100.

(Step S305)

The communicating portion 110 of the processing unit 100 receives thesound information transmitted by the reverberation sound monitor 7 andoutputs the received sound information to the information acquiringportion 122. The reverberation sound data acquiring portion 122 c of theinformation acquiring portion 122 acquires the sound information outputby the communicating portion 110 and outputs the acquired soundinformation to the measuring portion 124. The reverberation soundanalyzing portion 124 c of the measuring portion 124 acquires the soundinformation output by the reverberation sound data acquiring portion 122c and derives a measurement condition on the basis of the acquired soundinformation. The reverberation sound analyzing portion 124 c outputsinformation representing the derived measurement condition to the timingderiving portion 124 d.

(Step S306)

The timing deriving portion 124 d acquires the information representingthe measurement condition output by the timing deriving portion 124 d,creates control information including the acquired informationrepresenting the measurement condition, and outputs the created controlinformation to the communicating portion 110. The communicating portion110 transmits the control information output by the timing derivingportion 124 d to the excitation laser device 1.

(Step S307)

The excitation laser device 1 acquires the control informationtransmitted by the processing unit 100 and outputs excitation laserlight according to the measurement condition included in the acquiredcontrol information.

(Operation of Laser-Induced Vibration Wave Measuring System 20 (Part 4))

FIG. 17 is a flowchart showing an example (part 4) of the operation ofthe laser-induced vibration wave measuring system of the firstembodiment. FIG. 17 shows a process of determining whether or not alocation of the inspection target M irradiated with the excitation laserlight is faultless by processing vibration data.

(Step S401)

The communicating portion 110 of the processing unit 100 receives thevibration data (the number of vibrations) transmitted by the measurementlaser device 2 and outputs the received vibration data to theinformation acquiring portion 122. The vibration data acquiring portion122 d of the information acquiring portion 122 acquires the vibrationdata output by the communicating portion 110.

(Step S402)

The vibration data acquiring portion 122 d outputs the acquiredvibration data to the analyzing portion 126. The data processing portion126 a of the analyzing portion 126 extracts data of a time period inwhich measurement is performed from the vibration data on the basis ofthe vibration data output by the vibration data acquiring portion 122 dand the measurement condition output by the timing deriving portion 124d.

(Step S403)

The data processing portion 126 a removes noise caused by an unexpectedmeasurement failure from the extracted time period data by removing areduction amount arbitrarily determined from the maximum amount ofdisplacement of vibration generated by the excitation laser. Here, anexample of the reduction amount is 1/10, 1/100, or the like.

(Step S404)

The data processing portion 126 a determines whether or not the acquiredvibration data includes unexpected noise. The data processing portion126 a determines that the data determined to include the unexpectednoise is invalid data and removes the invalid data.

(Step S405)

The determining portion 126 b inspects the faultlessness of the portionof the inspection target M irradiated with the excitation laser light onthe basis of the frequency spectrum output by the data processingportion 126 a.

(Step S406)

The display portion 130 displays a result of inspecting thefaultlessness of the portion of the inspection target M irradiated withthe excitation laser light.

After the processing of step S406 is completed, the timing derivingportion 124 d derives a timing on the basis of information representingan amount of adjustment of a distance between the lens 12 a and the lens12 b, information representing an amount of adjustment of a distancebetween the lens 12 c and the lens 12 d, and time information requiredfor adjusting an inter-lens distance output by the condensing positionderiving portion 124 a, information representing a result of selectingan irradiation location output by the irradiation location analyzingportion 124 b, and information representing a measurement conditionoutput by the reverberation sound analyzing portion 124 c and proceedsto the next process of radiating the excitation laser light on the basisof the derived timing. The timing deriving portion 124 d transmitsinformation representing the derived timing from the communicatingportion 110 to the excitation laser device 1, the galvano scanner unit3, the biaxial mirror unit 5, the excitation laser condensing unit 10,and the measurement laser condensing unit 11. A laser irradiationadjusting portion of the excitation laser device 1 acquires informationrepresenting a timing transmitted by the processing unit 100 andcorrects a timing at which the excitation laser light is output byadjusting a master clock, the physical shutter, or the like on the basisof the acquired information representing the timing. A drive adjustingportion of each of the galvano scanner unit 3, the biaxial mirror unit5, the excitation laser condensing unit 10, and the measurement lasercondensing unit 11 acquires the information representing the timingtransmitted by the processing unit 100 and performs a drive operation atan appropriate speed and at an appropriate time on the basis of theacquired information representing the timing.

In the flowchart shown in FIG. 17 , step S403 and step S404 mayinterchange.

Although a case in which the reverberation sound monitor 7 measures asound generated by irradiating the inspection target M with theexcitation laser light has been described in the above-describedembodiment, the present invention is not limited to this example. Forexample, the reverberation sound monitor 7 may be configured to measurea sound generated by irradiating the inspection target M with themeasurement laser light.

Although a case in which the reverberation sound monitor 7 is attachedto the biaxial mirror unit 5 has been described in the above-describedembodiment, the present invention is not limited to this example. Forexample, the reverberation sound monitor 7 may be attached to thegalvano scanner unit 3 or may be attached to the excitation laser device1 or the measurement laser device 2.

Although a case in which a so-called acoustic measurement device such asa microphone is used has been described as an example of thereverberation sound monitor 7 in the above-described embodiment, thepresent invention is not limited to this example. For example, anacceleration sensor may be installed as the reverberation sound monitor7 in the laser-induced vibration wave measuring system, so that a soundmay be measured by measuring vibration of a housing or an opticalelement due to the reverberation sound.

Although a case in which the mirror 8 a bends the optical path of theexcitation laser light at a 90-degree angle, the mirror 8 b bends theoptical path of the distance measurement laser light at a 90-degreeangle, and the mirror 8 c bends the optical path of the excitation laserlight at a 90-degree angle has been described in the above-describedembodiment, the present invention is not limited to this example. Forexample, the optical system may be designed so that the mirror 8 a bendsthe optical path of the excitation laser light at any angle such as 30deg or 60 deg according to the design of an optical element. Also, theoptical system may be designed so that the mirror 8 b bends the opticalpath of the distance measurement laser light at any angle such as 30 degor 60 deg according to the design of an optical element. Also, theoptical system may be designed so that the mirror 8 c bends the opticalpath of the excitation laser light at any angle such as 30 deg or 60 degaccording to the design of an optical element.

Although a case in which the excitation laser condensing unit 10includes the lens 12 a and the lens 12 b has been described in theabove-described embodiment, the present invention is not limited to thisexample. For example, the excitation laser condensing unit 10 mayinclude one single lens or three or more combined lenses. A condensingposition or a condensing degree may be adjusted by adjusting aninstallation position of one single lens or three or more combinedlenses. The lens may be a convex lens or a concave lens.

Although a case in which the measurement laser condensing unit 11includes the lens 12 c and the lens 12 d has been described in theabove-described embodiment, the present invention is not limited to thisexample. For example, the measurement laser condensing unit 11 mayinclude one single lens or three or more combined lenses. A condensingposition or a condensing degree may be adjusted by adjusting aninstallation position of one single lens or three or more combinedlenses. The lens may be a convex lens or a concave lens.

Although a case in which the galvano scanner unit 3 includes the twomirrors of the galvano scanner mirror 4 a and the galvano scanner mirror4 b has been described in the above-described embodiment, the presentinvention is not limited to this example. For example, the galvanoscanner unit 3 may include one galvano scanner mirror or may includethree or more galvano scanner mirrors.

Although a case in which the biaxial mirror unit 5 includes the biaxialmirror has been described in the above-described embodiment, the presentinvention is not limited to this example. For example, the biaxialmirror unit 5 may include two or more biaxial mirrors.

Although a case in which the laser-induced vibration wave measuringsystem 20 of the first embodiment causes the galvano scanner unit 3 andthe biaxial mirror unit 5 to be combined and causes either or both ofthe excitation laser light and the measurement laser light to be swepthas been described in the above-described embodiment, the presentinvention is not limited to this example. For example, one of thegalvano scanner unit 3 and the biaxial mirror unit 5 may cause either orboth of the excitation laser light and the measurement laser light to beswept.

Although a case in which the irradiation location analyzing portion 124b of the processing unit 100 acquires a result of selecting anirradiation location on the basis of a scheduled laser irradiationlocation image captured by the imaging device 13 has been described inthe above-described embodiment, the present invention is not limited tothe example. For example, the result of selecting the irradiationlocation may be acquired on the basis of information acquired by adevice that can acquire information of the surface of the inspectiontarget M such as a 3D scanner or thermography.

Although a case in which the irradiation location analyzing portion 124b of the processing unit 100 selects a scheduled laser irradiationlocation that has no uneven shadow, is flat, has the same wetness asother scheduled laser irradiation locations, and has no appendage on thebasis of the scheduled laser irradiation location image has beendescribed in the above-described embodiment, this is an example andselection items, selection criteria, and the number of scheduled laserirradiation locations to be selected can be arbitrarily determined bythe user.

Although a case in which the data processing portion 126 a sets anexponential function as an evaluation function and determines that datafor which its trend and a correlation coefficient of a certain level orhigher cannot be obtained include unexpected noise has been described inthe above-described embodiment, the present invention is not limited tothis example. For example, the reverberation sound monitor 7 is allowedto measure an environmental sound. The data processing portion 126 a ofthe processing unit 100 may be configured to remove the noise componentincluded in the vibration data on the basis of the environmental soundmeasured by the reverberation sound monitor 7. Also, a vibrationmeasuring device for measuring the vibration of the laser-inducedvibration wave measuring system 20 itself may be provided. The dataprocessing portion 126 a of the processing unit 100 may be configured toremove the noise component included in the vibration data on the basisof the vibration measured by the vibration measuring device.

Although a case in which the determining portion 126 b determines thefaultlessness of the location irradiated with the excitation laser lightusing a result of performing an FFT on the vibration data in the dataprocessing portion 126 a has been described in the above-describedembodiment, the present invention is not limited to this example. Forexample, the determining portion 126 b may be configured to determinefaultlessness of the location irradiated with the excitation laser lightusing a result of wavelet analysis performed by the data processingportion 126 a.

In the above-described embodiment, machine learning may be applied to aprocess of the information processing portion 120.

The laser-induced vibration wave measuring system 20 according to thefirst embodiment measures the inspection target M on the basis ofvibration generated when the inspection target M has been irradiatedwith excitation laser light. The laser-induced vibration wave measuringsystem 20 includes a condensing position deriving portion configured toderive an amount of adjustment of a condensing position of an excitationlaser condensing unit configured to condense the excitation laser lighton the basis of a distance between a laser device configured to radiatethe excitation laser light and an irradiation location of the excitationlaser light and a communicating portion configured to transmit controlinformation including information representing the amount of adjustmentto the excitation laser condensing unit. According to thisconfiguration, because a condensing diameter of the excitation laserlight output from the excitation laser condensing unit can be reduced,an irradiation intensity of the excitation laser light per unit area canbe improved. Because the intensity of a signal in the frequency spectrumcan be improved, the accuracy of measurement of the inspection target Mcan be improved.

Also, the laser-induced vibration wave measuring system 20 furtherincludes an irradiation location analyzing portion configured to selecta location to be irradiated with the excitation laser light on the basisof information representing an image of a location of the inspectiontarget M scheduled to be irradiated with the excitation laser light. Thecommunicating portion transmits control information includinginformation representing the location to be irradiated with theexcitation laser light selected by the irradiation location analyzingportion to a sweep device configured to sweep the excitation laserlight.

According to this configuration, because it is possible to reduce noisewhen a location which should not be irradiated with the excitation laserlight is irradiated with the excitation laser light, the accuracy ofmeasurement of the inspection target M can be improved.

Also, the laser-induced vibration wave measuring system 20 furtherincludes the reverberation sound data acquiring portion 122 c configuredto acquire time-series data of a reverberation sound generated when theinspection target M has been irradiated with the excitation laser light;and the reverberation sound analyzing portion 124 c configured toacquire a timing at which the inspection target M is irradiated with theexcitation laser light on the basis of an intensity of the reverberationsound of the time-series data of the reverberation sound acquired by thereverberation sound data acquiring portion 122 c. The communicatingportion transmits control information including the informationrepresenting the timing acquired by the reverberation sound analyzingportion 124 c to the excitation laser device 1 configured to radiate theexcitation laser light.

According to this configuration, the reverberation sound analyzingportion can acquire a timing at which a time range in which an intensityof the reverberation sound is less than or equal to a reverberationsound threshold value is widened on the basis of the intensity of thereverberation sound of the time-series data of the reverberation soundand can transmit control information including information representingthe acquired timing to the excitation laser device 1. The excitationlaser device 1 receives the control information and radiates theexcitation laser light at the timing included in the received controlinformation. Because the excitation laser device 1 can cause theexcitation laser light to be radiated at a timing when the time range inwhich the influence of the reverberation sound is small is widened, itis possible to reduce the influence of the reverberation sound generatedwhen a cycle at which the excitation laser light is radiated is short.Because it is possible to reduce a noise component of an amplitudewaveform with respect to a time period of vibration that occurs when theinspection target M is irradiated with the excitation laser light, theaccuracy of measurement of the inspection target M can be improved.

Also, the laser-induced vibration wave measuring system 20 furtherincludes a data removing portion configured to remove data during apredetermined time period from a time at which the inspection target Mhas been irradiated with the excitation laser light from measurementdata of vibration generated in the inspection target M. According tothis configuration, because it is possible to reduce the influence ofnoise generated immediately after the irradiation with the excitationlaser light, the accuracy of measurement of the inspection target M canbe improved.

Also, the laser-induced vibration wave measuring system 20 furtherincludes a noise removing portion configured to remove noise frommeasurement data of vibration on the basis of a correlation coefficientbetween the measurement data of vibration generated in the inspectiontarget M and an evaluation function of the measurement data. Accordingto this configuration, because it is possible to reduce the influence ofnoise that has been unexpectedly generated, the accuracy of measurementof the inspection target M can be improved.

Also, the laser-induced vibration wave measuring system 20 furtherincludes a determining portion configured to determine faultlessness ofa location of the inspection target M irradiated with the excitationlaser light on the basis of measurement data acquired when vibration hasbeen induced in the inspection target M by irradiating the inspectiontarget M with the excitation laser light and measurement data acquiredwhen the inspection target M has not been irradiated with the excitationlaser light that induces the vibration. According to this configuration,because the number of noise components of the measurement data acquiredwhen the inspection target M has been irradiated with the excitationlaser light can be reduced on the basis of the measurement data acquiredwhen the inspection target M is not irradiated with the excitation laserlight, the accuracy of measurement of the inspection target M can beimproved.

Second Embodiment (Laser-Induced Vibration Wave Measuring System)

FIG. 1 is applicable to an example of a laser-induced vibration wavemeasuring system 20 a of a second embodiment. However, a processing unit100 a is provided instead of the processing unit 100.

(Processing Unit 100 a)

FIG. 18 is a block diagram showing an example of the processing unit ofthe laser-induced vibration wave measuring system of the secondembodiment.

The processing unit 100 a is implemented by a device such as a personalcomputer, a server, a smartphone, a tablet computer, or an industrialcomputer.

The processing unit 100 a includes, for example, a communicating portion110, an information processing portion 120 a, a display portion 130, anda storing portion 140 a.

The information processing portion 120 a is, for example, a softwarefunction portion implemented by a processor such as a CPU executing aprogram 142 a stored in a storing portion 140 a. Also, all or a part ofthe information processing portion 120 a may be implemented by hardwaresuch as an LSI circuit, an ASIC, or an FPGA or may be implemented by acombination of the software function portion and the hardware.

The information processing portion 120 a includes, for example, aninformation acquiring portion 122, a measuring portion 124, and ananalyzing portion 126 d.

(Analyzing Portion 126 d)

The analyzing portion 126 d includes a data processing portion 126 c anda determining portion 126 b.

The data processing portion 126 c acquires a measurement conditionoutput by the timing deriving portion 124 d and vibration data output bythe vibration data acquiring portion 122 d and processes the acquiredvibration data on the basis of the acquired measurement condition.

Here, when the same location of the inspection target M is measured, thevibration data may be vibration data obtained in a single operation ofradiating excitation laser light or vibration data obtained in aplurality of operations of radiating excitation laser light. In thisregard, when vibration data obtained in a plurality of operations ofradiating excitation laser light is used, the data processing portion126 c may average or integrate the vibration data output by thevibration data acquiring portion 122 d.

The data processing portion 126 c extracts data of time periods M1, M2,and the like in which measurement is performed from the vibration dataon the basis of the measurement condition output by the timing derivingportion 124 d. Also, the data processing portion 126 c removes areduction amount arbitrarily determined from the maximum amount ofdisplacement of vibration generated by the excitation laser afterirradiation with the excitation laser light from the extracted data ofthe time periods M1, M2, and the like. Here, the reduction amount is,for example, 1/10, 1/100, or the like, and is, for example, data for apredetermined time period such as a period of 0.5 ms to 10 ms. Becauseit is possible to reduce an influence of noise generated immediatelyafter irradiation with the excitation laser light by removing areduction amount arbitrarily determined from the maximum amount ofdisplacement of vibration generated by the excitation laser afterirradiation with the excitation laser light, the accuracy of measurementcan be improved.

Also, the data processing portion 126 c reduces unexpected noise fromthe acquired vibration data. Specifically, the data processing portion126 c reduces a noise component of the acquired vibration data bysumming the acquired vibration data and data obtained by shifting aphase of the vibration data. Here, the amount of phase shift is preset.

FIG. 19 is a diagram showing an example of noise removal of thelaser-induced vibration wave measuring system 20 a of the secondembodiment. In FIG. 19 , (a) is acoustic noise, (b) is a signal obtainedby shifting a phase of the acoustic noise of (a) by π, and (c) is asignal obtained by summing (a) and (b). Returning to FIG. 18 , thedescription will be continued.

The data processing portion 126 c acquires valid data obtained byreducing the noise component of the vibration data.

Here, when the acquired valid data is data obtained by irradiating thesame location of the inspection target M with excitation laser light aplurality of times, the data processing portion 126 c removes noiseunexpectedly generated by irradiating the same location of theinspection target M with excitation laser light a plurality of timesfrom the valid data. Specifically, because the number of times thatnoise unexpectedly generated by irradiating the same location withexcitation laser light a plurality of times is mixed in the vibrationdata is less than the total number of times of irradiation, the dataprocessing portion 126 c removes data including noise unexpectedlygenerated by irradiating the same location with excitation laser light aplurality of times by extracting waveforms of a threshold value or morefrom the largest coefficient of a correlation with a waveform obtainedby performing a time average operation on the vibration data. The dataprocessing portion 126 c outputs information representing a frequencyspectrum to the determining portion 126 b.

FIG. 14 is applicable to a process of adjusting a distance between alens 12 a and a lens 12 b of the excitation laser condensing unit 10 anda distance between a lens 12 c and a lens 12 d of the measurement lasercondensing unit 11.

FIG. 15 is applicable to a process in which a galvano scanner unit 3 anda biaxial mirror unit 5 controls an irradiation location of theinspection target M.

FIG. 16 is applicable to a process of controlling an output timing ofexcitation laser light.

It is possible to apply FIG. 17 as an example of an operation of thelaser induced vibration wave measuring system 20 a. In this regard, instep S404, noise is removed from vibration measurement data on the basisof measurement data of vibration generated in the inspection target Mand data obtained by shifting a phase of time-series data of themeasurement data.

In the above-described embodiment, machine learning may be applied to aprocess of the information processing portion 120 a.

The laser-induced vibration wave measuring system 20 a according to thesecond embodiment measures the inspection target M on the basis ofvibration generated when the inspection target M has been irradiatedwith excitation laser light. The laser-induced vibration wave measuringsystem 20 a includes a condensing position deriving portion configuredto derive an amount of adjustment of a condensing position of anexcitation laser condensing unit configured to condense the excitationlaser light on the basis of a distance between a laser device configuredto radiate the excitation laser light and an irradiation location of theexcitation laser light and a communicating portion configured totransmit control information including information representing theamount of adjustment to the excitation laser condensing unit. Accordingto this configuration, because a condensing diameter of the excitationlaser light output from the excitation laser condensing unit can bereduced, an irradiation intensity of the excitation laser light per unitarea can be improved. Because the intensity of a signal in the frequencyspectrum can be improved, the accuracy of measurement of the inspectiontarget M can be improved.

Also, the laser-induced vibration wave measuring system 20 a furtherincludes a noise removing portion configured to remove noise frommeasurement data of vibration on the basis of the measurement data ofthe vibration generated in the inspection target M and data obtained byshifting a phase of time-series data of the measurement data. Because atleast a part of the noise component is canceled out and the influence ofnoise can be reduced by causing the measurement data of the vibrationgenerated in the inspection target M and the data obtained by shiftingthe phase of the time-series data of the measurement data to besuperimposed, the accuracy of measurement of the inspection target M canbe improved.

Modified Example 1 (Laser-Induced Vibration Wave Measuring System)

Modified examples of the first and second embodiments will be described.Modified Example 1 of the first embodiment includes one or morehousings, each of which stores elements constituting the laser-inducedvibration wave measuring system 20 of the first embodiment. ModifiedExample 1 of the second embodiment includes one or more housings, eachof which stores elements constituting the laser-induced vibration wavemeasuring system 20 a of the second embodiment. Here, Modified Example 1of the first embodiment will be continuously described as an example.

FIG. 20 is a diagram showing Example 1 of the laser-induced vibrationwave measuring system of Modified Example 1 of the first embodiment. Asshown in FIG. 20 , the laser-induced vibration wave measuring system ofModified Example 1 of the first embodiment includes three housings. Thethree housings are referred to as a first housing H01, a second housingH02, and a third housing H03. Preferably, the first housing H01, thesecond housing H02, and the third housing H03 are covered with asoundproof wall to be described below.

The excitation laser device 1 and the mirror 8 a are stored in the firsthousing H01. Because an influence on the measuring system stored in thesecond housing H02 to be described below is small and an influence on ameasurement result is small even if the excitation laser device 1 andthe mirror 8 a stored in the first housing H01 are affected by noiseoutside the laser-induced vibration wave measuring system 20 (here, thefirst housing H01), the surroundings thereof do not need to be coveredwith the soundproof wall. The excitation laser device 1 outputsexcitation laser light. The optical path of the excitation laser lightoutput by the excitation laser device 1 is bent by the mirror 8 a (bentat a 90-degree angle in FIG. 20 ) and moves from a laser light port LP01formed at the boundary between the first housing H01 and the secondhousing H02 to the second housing. The laser light port LP01 will bedescribed below.

The second housing H02 includes the measurement laser device 2, thegalvano scanner unit 3, the mirror 8 c, the distance measurement laserdevice 9, the excitation laser condensing unit 10, and the measurementlaser condensing unit 11. Although not shown in FIG. 20 , thereverberation sound monitor 7, the mirror 8 b, the imaging device 13,and the processing unit 100 may be provided in the second housing H02. Adevice that performs a measurement process is stored in the secondhousing H02 and an influence of noise outside the laser-inducedvibration wave measuring system 20 (here, the second housing H02) tendsto affect a measurement result. Thus, it is preferable that thesurroundings of the second housing H02 be covered with a soundproof wallSW.

The excitation laser light from the first housing H01 passes through thelaser light port LP01 and enters the excitation laser condensing unit10. The excitation laser condensing unit 10 condenses the excitationlaser light output by the excitation laser device 1. An optical path ofthe excitation laser light condensed by the excitation laser condensingunit 10 is bent by the mirror 8 c (bent at a 90-degree angle in FIG. 20) and moves to the galvano scanner unit 3.

On the other hand, the measurement laser device 2 outputs themeasurement laser light so that vibration induced in the inspectiontarget M is detected. The measurement laser condensing unit 11 condensesthe measurement laser light output by the measurement laser device 2.The measurement laser light condensed by the measurement lasercondensing unit 11 moves to the galvano scanner unit 3. The galvanoscanner unit 3 adjusts an optical path of either or both of theexcitation laser light and the measurement laser light in any directionand angle. Either or both of the excitation laser light and themeasurement laser light output by the galvano scanner unit 3 move from alaser light port LP02 formed at the boundary between the second housingH02 and the third housing H03 to the third housing. The laser light portLP02 will be described below.

The third housing H03 includes the biaxial mirror unit 5. The biaxialmirror unit 5 includes the biaxial mirror 6 and adjusts the biaxialmirror 6. A laser light port for emission configured to guide a laser tothe inspection target M is provided in the third housing H03. Becausethe biaxial mirror unit 5 is stored in the third housing H03, it ispreferable that the third housing 03 be covered with the soundproof wallSW. Also, the biaxial mirror unit 5 stored in the third housing H03 isstored within the third housing H03 in a configuration in whichvibration is difficult due to an influence of noise outside thelaser-induced vibration wave measuring system 20 (here, the thirdhousing H03), the surroundings of the third housing H03 do not need tobe covered with a soundproof wall. For example, when the biaxial mirrorunit 5 is a heavy object and a vibration suppressing mechanism isprovided, the soundproof wall SW is not essential because an influenceof external noise is reduced.

FIG. 20 shows an example in which the surroundings of the third housingH03 are not covered with the soundproof wall SW and a dome-shaped(kamaboko-shaped) laser light port is provided. The dome-shaped laserlight port is preferably made of a material similar to that of a laserwindow LW to be described below or is preferably coated with similarantireflection coating. The laser light (at least one or all ofexcitation laser light, measurement laser light, and distancemeasurement laser light) output to the biaxial mirror unit 5 is radiatedtoward an irradiation position of the inspection target M set by thebiaxial mirror unit 5 from the laser light port formed in the thirdhousing H03 to the outside of the third housing H03.

FIG. 21 is a diagram showing Example 2 of the laser-induced vibrationwave measuring system of Modified Example 1 of the first embodiment.Example 2 of the laser-induced vibration wave measuring system ofModified Example 1 of the first embodiment includes two housings. Thetwo housings are referred to as a third housing H03 and a fourth housingH04. Also, FIG. 21 shows an example in which the third housing 03 doesnot include a dome-shaped (kamaboko-shaped) laser light port.

Example 2 of the laser-induced vibration wave measuring system ofModified Example 1 of the first embodiment is a configuration in whichthe first housing H01 and the second housing H02 of Example 1 shown inFIG. 20 are integrated. That is, the fourth housing H04 is aconfiguration in which the first housing H01 and the second housing H02of Example 1 shown in FIG. 20 are integrated.

The fourth housing H04 includes the excitation laser device 1, themirror 8 a, the measurement laser device 2, the galvano scanner unit 3,the mirror 8 c, the distance measurement laser device 9, the excitationlaser condensing unit 10, and the measurement laser condensing unit 11.Although not shown in FIG. 21 , the reverberation sound monitor 7, themirror 8 b, the imaging device 13, and the processing unit 100 may beprovided in the fourth housing H04. Because a device for performing ameasurement process is stored in the fourth housing H04, it ispreferable that the surroundings of the device be covered with thesoundproof wall SW.

At least one or all of the excitation laser light, the measurement laserlight, and the distance measurement laser light output by the galvanoscanner unit 3 move from a laser light port LP03 formed at the boundarybetween the fourth housing H04 and the third housing H03 to the thirdhousing H03. The laser light port LP03 will be described below.

In Example 2 of the laser-induced vibration wave measuring system ofModified Example 1 of the first embodiment, vibration originating fromthe excitation laser may affect a device for performing a measurementprocess because the excitation laser device 1 is accommodated within thefourth housing H04. Thus, in Example 2 of the laser-induced vibrationwave measuring system of Modified Example 1 of the first embodiment, itis preferable to use a high-power laser of a silent type semiconductorlaser (laser diode (LD)) excitation scheme as the excitation laserdevice 1 as compared with a case in which a flash lamp excitation schemeis used.

FIG. 22 is a diagram showing Example 3 of the laser-induced vibrationwave measuring system of Modified Example 1 of the first embodiment.Example 3 of the laser-induced vibration wave measuring system ofModified Example 1 of the first embodiment is a configuration in whichthe first housing H01, the second housing H02, and the third housing H03are integrated in Example 1 of the laser-induced vibration wavemeasuring system of Modified Example 1 of the first embodiment or aconfiguration in which the fourth housing H04 and the third housing H03are integrated in Example 2 of the laser-induced vibration wavemeasuring system of Modified Example 1 of the first embodiment. Ahousing in which the first housing H01, the second housing H02, and thethird housing H03 are integrated or a housing in which the fourthhousing H04 and the third housing H03 are integrated is referred to as afifth housing H05.

The fifth housing H05 includes the excitation laser device 1, the mirror8 a, the measurement laser device 2, the galvano scanner unit 3, themirror 8 c, the distance measurement laser device 9, the excitationlaser condensing unit 10, the measurement laser condensing unit 11, andthe biaxial mirror unit 5. Although not shown in FIG. 22 , thereverberation sound monitor 7, the mirror 8 b, the imaging device 13,and the processing unit 100 may be provided in the fifth housing H05.Because a device for performing a measurement process is stored in thefifth housing H05, it is preferable that the surroundings thereof becovered with the soundproof wall SW.

The biaxial mirror unit 5 includes the biaxial mirror 6 and adjusts thebiaxial mirror 6. The laser light (at least one or all of excitationlaser light, measurement laser light, and distance measurement laserlight) output to the biaxial mirror unit 5 is radiated toward anirradiation position of the inspection target M set by the biaxialmirror unit 5 from the laser light port LP04 formed in the fifth housingH05 to the outside of the fifth housing H05.

(Laser Light Port)

The laser light ports shown in Examples 1 to 3 of the laser-inducedvibration wave measuring system of Modified Example 1 of the firstembodiment will be described. Here, any housing among the first housingH01, the second housing H02, the third housing H03, the fourth housingH04, and the fifth housing H05 is referred to as a housing H. Also, thelaser light port LP01, the laser light port LP02, the laser light portLP03, and the laser light port LP04 have similar configurations. Anylaser light port among the laser light port LP01, the laser light portLP02, the laser light port LP03, and the laser light port LP04 isreferred to as a laser light port LP.

FIGS. 23A and 23B are diagrams showing examples of the laser light portsLP shown in Examples 1 to 3 of the laser-induced vibration wavemeasuring system of Modified Example 1 of the first embodiment.

FIG. 23A is a diagram showing a side view of the laser light port LP ofthe laser-induced vibration wave measuring system of Modified Example 1of the first embodiment.

The laser light port LP includes a spacer SP, a laser window LW, and apressing plate PP. The spacer SP is bolted to the housing H. Here, it ispreferable that the spacer SP be bolted to the housing H or welded tothe housing H instead of being bolted to the housing H.

It is preferable that the laser window LW be made of a material havinghigh laser light transmittance, withstand high-intensity laser light,and have weather resistance, mechanical rigidity, and chemicalstability. An example of the laser window LW is quartz glass. It isdesirable that the laser window LW be coated with an antireflection filmso that reflection on a refractive index interface is curbed. To preventthe laser window LW from affecting measurement by the reflection of themeasurement laser light on the refractive index interface, it isdesirable that the laser window LW have an angle of a few degrees(hereinafter referred to as an “installation angle”) with respect to adirection perpendicular to a movement direction of the laser window LW.In this regard, the laser window LW may be parallel to the directionorthogonal to the direction in which the laser window LW moves, i.e.,the installation angle may be 0 degree. The installation angle ispreferably 5 to 12 degrees and more preferably 8 to 10 degrees. Forexample, the installation angle is 10 degrees.

The pressing plate PP is a member for fixing the laser window LW to thespacer SP.

FIG. 23B is a diagram showing a front view of the laser light port LP ofthe laser-induced vibration wave measuring system of Modified Example 1of the first embodiment. FIG. 23B is a diagram viewed from the directionof an arrow E in FIG. 23A. According to FIG. 23B, the laser window LW isfixed by the spacer SP in which an opening is formed and the pressingplate PP in which an opening is formed so that an opening is formed inthe housing H and the laser window LW is exposed from the formedopening. Although a case in which a portion where the laser window LW isexposed is circular is shown in FIGS. 23A and 23B, the present inventionis not limited to this example. For example, the exposed portion of thelaser window LW may be an ellipse, a rectangle such as a quadrangle, ora polygon.

(Range of Installation Angle)

Here, a range of a desired installation angle of the laser window LWwill be described.

FIG. 24 is a diagram showing the minimum installation angle of the laserwindow LW and FIG. 25 is a diagram showing the maximum installationangle of the laser window LW.

It is preferable that the range of the installation angle be a rangewhich is greater than or equal to an angle of (ΔD>d+d′) at which “laserlight emitted from the laser device” does not overlap “laser lightreflected on the laser window LW” at a position where the laser deviceemits the laser light as shown in FIG. 24 and which is less than orequal to an angle at which a diameter of an opening through which “laserlight emitted from the laser device” can be transmitted is secured(2d′<A′) as shown in FIG. 25 . That is, when the installation angle isθ, Eq. (1) is satisfied.

[Math.1] $\begin{matrix}{{\frac{1}{2}{\tan^{- 1}\left\lbrack \frac{d + {{cos2\theta}\left( {d + {L_{dis}{tan\theta}_{Laser}}} \right)}}{L} \right\rbrack}} \leq \theta \leq {\frac{\pi}{2} - {\sin^{- 1}\left\lbrack \frac{2\left( {d + {L_{dis}{tan\theta}_{Laser}}} \right)}{A} \right\rbrack}}} & (1)\end{matrix}$

In Eq. (1), the angle is expressed in rad. By rewriting π/2 in Eq. (1)as 90 deg, it is possible to make a change to deg notation. d is a beamradius of the laser light, L is a distance from the laser device to thelaser window LW, L_(dis) is a distance until the laser light returnsfrom the laser device to a laser light emission position after beingreflected on the laser window LW, and θ_(Laser) is a laser divergenceangle. Here, θ_(Laser) can be ignored as long as the laser light isparallel light that moves straight without being expanded or narrowed.Also, θ is the installation angle of the laser window LW and the angledirectly facing the laser light is defined as 0 deg. A is the diameterof the laser window LW.

Eq. (1) can be simplified as shown in Eq. (2) in the case of parallellight (when θ_(Laser) can be ignored).

[Math.2] $\begin{matrix}{{\frac{1}{2}{\tan^{- 1}\left( \frac{2d}{L} \right)}\theta} \leq {\frac{\pi}{2} - {\sin^{- 1}\left( \frac{2d}{A} \right)}}} & (2)\end{matrix}$

In Modified Example 1 of the first embodiment, the shape of the housingH is not limited to a rectangular parallelepiped and any shape can beapplied. Also, the device stored in the housing H can be arbitrarilychanged.

Here, although a case in which the laser-induced vibration wavemeasuring system 20 of the first embodiment is stored in one or morehousings has been described as an example, the present invention is notlimited thereto. For example, a similar effect can be obtained even ifthe laser-induced vibration wave measuring system 20 a of the secondembodiment is stored in one or more housings.

According to Modified Example 1 of the first embodiment, the deviceconstituting the laser-induced vibration wave measuring system 20 isstored in one or more housings H, so that the accuracy of measurement ofthe inspection target M can be improved because soundproofingperformance can be improved.

Modified Example 2 (Laser-Induced Vibration Wave Measuring System)

In a laser-induced vibration wave measuring system of Modified Example 2of the first embodiment, the laser-induced vibration wave measuringsystem 20 of the first embodiment is mounted on a moving body.

FIG. 26 is a diagram showing an example of the laser-induced vibrationwave measuring system of Modified Example 2 of the first embodiment. Asshown in FIG. 26 , in the laser-induced vibration wave measuring systemof Modified example 2 of the first embodiment, the laser-inducedvibration wave measuring system 20 of the first embodiment is mounted ona moving body such as a truck 500. In addition to the moving body, atunnel TU is also shown in FIG. 26 . The moving body is located insidethe tunnel TU. In the example shown in FIG. 26 , the laser-inducedvibration wave measuring system 20 of the first embodiment is mounted onthe truck 500. Specifically, an equipment storage 250, a device housing300, and a biaxial mirror housing 400 are mounted on the truck 500.

The equipment storage 250 stores a power supply for devices included inthe laser-induced vibration wave measuring system 20, i.e., theexcitation laser device 1, the measurement laser device 2, the galvanoscanner unit 3, the biaxial mirror unit 5, the reverberation soundmonitor 7, and the distance measurement laser device 9, the excitationlaser condensing unit 10, the measurement laser condensing unit 11, theimaging device 13, and the processing unit 100, a cooling water chiller,and the processing unit 100 are stored. Because the device stored in theequipment storage 250 may become a noise source or a heat source, it isdesirable to store the device in an external housing different from thedevice housing 300. The device stored in the equipment storage 250 doesnot need to be managed in a warehouse, but it is desirable that thedevice be protected from rain and wind, i.e., the device not be exposedto rain and wind. Because the device stored in the equipment storage 250may serve as a heat source, it is preferable that the equipment storage250 be provided with either or both of a ventilation function and an airconditioning function.

The excitation laser device 1, the measurement laser device 2, thegalvano scanner unit 3, the reverberation sound monitor 7, the mirror 8a, the mirror 8 b, the mirror 8 c, the distance measurement laser device9, the excitation laser condensing unit 10, the measurement lasercondensing unit 11, and the imaging device 13 are stored in the devicehousing 300.

It is preferable that the surroundings of the device housing 300 becovered with a soundproof wall SW. Furthermore, it is desirable that thedevice housing 300 have dustproof and moistureproof functions.

However, because an operation sound becomes a noise source, it ispreferable to separate the excitation laser device 1 from the devicehousing 300 and store the excitation laser device 1 in a housingdifferent from the device housing 300. When the excitation laser device1 is separated from the device housing 300 and is stored in a housingdifferent from the device housing 300, the excitation laser light outputby the excitation laser device 1 may be sent to the device housing 300in which the measurement laser device 2 and the like are stored usingthe mirror 8 a. For example, as in Example 1 (FIG. 20 ) of ModifiedExample 1 described above, a configuration in which the excitation laserdevice 1 is stored in a housing different from the device that performsthe measurement process is an exemplary example.

The biaxial mirror unit 5 is stored in the biaxial mirror housing 400.It is preferable that the surroundings of the biaxial mirror housing 400be covered with a soundproof wall SW. Further, it is desirable that thebiaxial mirror housing 400 have dustproof and moistureproof functions.Although a case in which the biaxial mirror unit 5 is stored in thebiaxial mirror housing 400 different from the device housing 300 hasbeen described as an example in FIG. 26 , the present invention is notlimited thereto. As in Example 3 of Modified Example 1 (FIG. 22 ), thebiaxial mirror unit 5 may be stored within the device housing 300.

Typically, in the laser-induced vibration wave measuring system ofModified Example 2 of the first embodiment, the laser-induced vibrationwave measuring system of Modified Example 1 (Example 1, Example 2, andExample 3) of the first embodiment, i.e., the laser-induced vibrationwave measuring system 20 stored in the housing H (H01, H02, H03, H04,and H05), and the equipment storage 250 are mounted on the truck 500.

In the laser-induced vibration wave measuring system according toModified Example 2 of the first embodiment, the biaxial mirror unit 5stored in the biaxial mirror housing 400 radiate excitation laser lightand measurement laser light to an inner wall of the tunnel TU. Thebiaxial mirror unit 5 sweeps the excitation laser light and themeasurement laser light according to a preset sweep order.

Although a case in which the laser-induced vibration wave measuringsystem 20 is mounted on the truck 500 has been described in ModifiedExample 2 of the first embodiment, the present invention is not limitedto this example. The laser-induced vibration wave measuring system 20may be configured to be movable in a conventionally well-knowntechnique. The moving means is not limited to the presence or absence ofwheels. For example, the laser-induced vibration wave measuring system20 may be mounted on a moving body such as a wheelbarrow, an automobile,or a railway vehicle. Alternatively, the laser-induced vibration wavemeasuring system 20 may be configured to be movable by attaching themoving means (for example, wheels) thereto.

A case in which a power supply of the laser-induced vibration wavemeasuring system 20 is mounted on the same moving body as the devicehousing 300 and the biaxial mirror housing 400 has been described inModified Example 2 of the first embodiment, the present invention is notlimited to this example. For example, the power supply of thelaser-induced vibration wave measuring system 20 may be mounted on amoving body different from the moving body on which the device housing300 and the biaxial mirror housing 400 are mounted. When the powersupply of the laser-induced vibration wave measuring system 20 ismounted on a moving body different from the moving body on which thedevice housing 300 and the biaxial mirror housing 400 are mounted, themoving body on which the power supply is mounted is preferably providedwith anti-vibration measures.

Here, although a case in which the laser-induced vibration wavemeasuring system 20 of the first embodiment is mounted on a moving bodyhas been described as an example, the present invention is not limitedthereto. For example, a similar effect can be obtained when thelaser-induced vibration wave measuring system 20 a of the secondembodiment is mounted on a moving body.

According to Modified Example 2 of the first embodiment, thelaser-induced vibration wave measuring system 20 is mounted on themoving body, so that the movement can be facilitated and the inspectiontarget M can be easily measured.

Modified Example 3 (Laser-Induced Vibration Wave Measuring System)

Modified Example 3 of the first and second embodiments will bedescribed. In Modified Example 3 of the first embodiment, a soundproofwall is provided around some or all of the components constituting thelaser-induced vibration wave measuring system 20 of the firstembodiment. In Modified Example 1 of the second embodiment, a soundproofwall is provided around some or all of the components constituting thelaser-induced vibration wave measuring system 20 a of the secondembodiment. In other words, the components constituting thelaser-induced vibration wave measuring system 20 are stored in thelaser-induced vibration wave measuring system of Modified Example 1(Example 1, Example 2, or Example 3) described above, i.e., in each ofone or more housings H, and a soundproof wall is provided around a partor all of the housing H (H01, H02, H03, H04, or H05). Here, thedescription of Modified Example 3 of the first embodiment will becontinued as an example.

FIG. 27A is a diagram showing an example of a laser-induced vibrationwave measuring system of Modified Example 3 of the first embodiment. Atop view of the laser-induced vibration wave measuring system ofModified Example 3 of the first embodiment is shown in FIG. 27A. Asshown in FIG. 27A, the four sides of the laser-induced vibration wavemeasuring system 20 are covered with soundproof walls SW. It is alsopreferable to provide soundproof walls SW on the upper and lower sidesof the laser-induced vibration wave measuring system 20 in addition tothe four sides thereof so that the soundproofing performance isimproved. That is, it is preferable that the laser-induced vibrationwave measuring system 20 be covered with the soundproof wall SW.

FIG. 27B is a partially enlarged view of the laser-induced vibrationwave measuring system of Modified Example 3 of the first embodiment.FIG. 27B shows a partially enlarged view of A of FIG. 27A. Thesoundproof wall SW is configured to include a sound absorbing materialSM.

The sound absorbing material SM is a member that absorbs a sound. Anexample of the sound absorbing material SM is a porous material such asa sponge. The sound absorbing material SM covers the surroundings of thelaser-induced vibration wave measuring system 20 in close contact witheach other without any gap. It is desirable that the sound absorbingmaterial SM can just cover the surroundings of the laser-inducedvibration wave measuring system 20 or be slightly protruding.

The soundproof wall SW may be configured to include a frame plate FP inaddition to the sound absorbing material SM. The frame plate FP is aplate-shaped member with which the sound absorbing material SM iscovered. The frame plate FP is pressed against the sound absorbingmaterial SM and its end is fixed. For example, it is only necessary tofix the frame plate FP with bolts or fasteners. According to thisconfiguration, the sound absorbing material SM is fixed between thelaser-induced vibration wave measuring system 20 and the frame plate FP.It is desirable that the frame plate FP have a high (heavy) density andrigidity so that an external sound is reflected. An example of the frameplate FP is an iron plate.

FIG. 28A is a diagram showing Example 1 of the effect of a soundproofwall of the laser-induced vibration wave measuring system of ModifiedExample 3 of the first embodiment. In the example shown in FIG. 28A,sound pressure measurement results when the soundproof wall SW isprovided around the laser-induced vibration wave measuring system 20 ofthe first embodiment and when no soundproof wall SW is providedtherearound are shown.

In the evaluation shown in FIG. 28A, the measurement laser device 2, thegalvano scanner unit 3, the mirror 8 c, the distance measurement laserdevice 9, the excitation laser condensing unit 10, and the measurementlaser condensing unit 11 are stored within an appropriate housing (thesecond housing H02 described above) were stored and a soundproof wall SWwas attached to cover the surroundings (side walls) of the housing. Thelower surface of the housing is in close contact with the installationfloor and the upper surface of the housing is loaded with the firsthousing H01 as shown in FIG. 20 described above. The soundproof wall SWis not arranged around the excitation laser device 1 and the biaxialmirror unit 5. Sound insulation targets are an irradiation sound oflaser light (typically an excitation laser) and noise generated in anexternal environment (a passing sound of a car and an operation sound ofequipment such as a laser device power supply and a chiller forgenerating cooling water). A microphone was installed within the housingof the laser-induced vibration wave measuring system 20 (the secondhousing H02) and a sound range in the range of 0.01 kHz to 20 kHz wasset as a measurement target. According to FIG. 28A, it can be seen thatthe improvement of the sound insulation performance of about 35 dB isachieved by mounting the soundproof wall SW around the laser-inducedvibration wave measuring system 20.

FIG. 28B is a diagram showing Example 2 of the effect of a soundproofwall of the laser-induced vibration wave measuring system of ModifiedExample 3 of the first embodiment. In the example shown in FIG. 28B,sound pressure measurement results when a single soundproof wall SW ismounted around the laser-induced vibration wave measuring system 20 ofthe first embodiment, when double soundproof walls SW are mountedtherearound, and when no soundproof wall SW is mounted therearound areshown.

In the evaluation shown in FIG. 28B, the measurement laser device 2, thegalvano scanner unit 3, the mirror 8 c, the distance measurement laserdevice 9, the excitation laser condensing unit 10, and the measurementlaser condensing unit 11 were stored within an appropriate housing (thesecond housing H02 described above) and a soundproof wall SW wasattached to cover the surroundings (side walls) of the housing. Thelower surface of the housing is in close contact with the installationfloor and the upper surface of the housing is loaded with the firsthousing H01 as shown in FIG. 20 described above. The soundproof wall SWis not arranged around the excitation laser device 1 and the biaxialmirror unit 5. A sound insulation target is a source of a single soundof 0.1 kHz. A microphone was installed within the housing of thelaser-induced vibration wave measuring system 20 and a measurementtarget was 0.1 kHz. According to FIG. 28B, it can be seen that theimprovement of the sound insulation performance of about 21.6 dB isachieved by mounting a single soundproof wall SW around thelaser-induced vibration wave measuring system 20 (the second housingH02). Further, it can be seen that the improvement of the soundinsulation performance of about 13.3 dB is achieved by mounting doublesoundproof walls SW. Here, the soundproofing performance was improvedwhen the single soundproof wall SW was installed as compared with whenthe double soundproof walls SW were installed around the laser-inducedvibration wave measuring system 20. It is assumed that this is becausean added soundproof wall SW resonates and vibrates when the doublesoundproof walls SW are mounted. Thus, the soundproofing performance canbe improved by mounting the single soundproof wall having high soundinsulation performance or by taking into account resonance vibration ofthe soundproof wall SW.

FIG. 29 is a diagram showing Example 3 of the effect of a soundproofwall of the laser-induced vibration wave measuring system of ModifiedExample 3 of the first embodiment. In the example shown in FIG. 29 ,sound pressure measurement results when the soundproof wall SW ismounted around the laser-induced vibration wave measuring system 20 ofthe first embodiment and when no soundproof wall SW is mountedtherearound are shown.

In the evaluation shown in FIG. 29 , the biaxial mirror unit 5 wasstored in an appropriate housing (the third housing H03 described above)and the soundproof wall SW was attached to cover the surroundings (sidewalls) and the upper surface of the housing. Also, the lower surface isinstalled on the floor. Also, the measurement laser device 2, thegalvano scanner unit 3, the mirror 8 c, the distance measurement laserdevice 9, the excitation laser condensing unit 10, the measurement lasercondensing unit 11, and the excitation laser device 1 are stored in anappropriate housing (the first housing H01 or the second housing H02 tobe described below) and a soundproof wall is arranged therearound. Asound insulation target is an irradiation sound of a laser. A microphonewas installed inside the third housing H03 and a sound range in therange of 0 kHz to 20 kHz was a measurement target. According to FIG. 29, it can be seen that the improvement of the sound insulationperformance of about 18 dB is achieved by mounting the soundproof wallSW around the third housing H03.

According to Modified Example 3 of the first embodiment, thesoundproofing performance can be improved by mounting the soundproofwall SW around the laser-induced vibration wave measuring system 20, sothat the accuracy of measurement of the inspection target M can beimproved.

Here, although a case in which the soundproof wall SW is provided aroundthe laser-induced vibration wave measuring system 20 of the firstembodiment has been described as an example, the present invention isnot limited thereto. For example, a similar effect can be obtained evenif the soundproof wall SW is provided around the laser-induced vibrationwave measuring system 20 a of the second embodiment.

(Operation of Laser-Induced Vibration Wave Measuring System 20)

FIG. 30 is a sequence chart showing an example of an operation of thelaser induced vibration wave measuring system of the first embodiment.FIG. 30 shows a process of adjusting a condensing position of theexcitation laser condensing unit 10, controlling a laser irradiationlocation on the inspection target M using the galvano scanner unit 3 andthe biaxial mirror unit 5, and radiating a laser. That is, a process inwhich FIGS. 14 and 15 of the first embodiment are linked will bedescribed. Here, FIGS. 14 and 15 are appropriately referred to.

(Step S501)

An irradiation area is designated.

(Step S502)

Steps S101 and S102 of FIG. 14 are executed.

(Step S503)

The communicating portion 110 of the processing unit 100 receivesirradiation distance information transmitted by the distance measurementlaser device 9 and outputs the received irradiation distance informationto the information acquiring portion 122. The irradiation distance dataacquiring portion 122 a of the information acquiring portion 122acquires the irradiation distance information output by thecommunicating portion 110 and outputs the acquired irradiation distanceinformation to the measuring portion 124. The condensing positionderiving portion 124 a of the measuring portion 124 acquires theirradiation distance information output by the irradiation distance dataacquiring portion 122 a and acquires an inter-lens distance between thelens 12 a and the lens 12 b associated with the acquired irradiationdistance information from the inter-lens distance table 144 stored inthe storing portion 140.

The communicating portion 110 of the processing unit 100 receives theirradiation distance information transmitted by the distance measurementlaser device 9 and outputs the received irradiation distance informationto the information acquiring portion 122. The irradiation distance dataacquiring portion 122 a of the information acquiring portion 122acquires the irradiation distance information output by thecommunicating portion 110 and outputs the acquired irradiation distanceinformation to the measuring portion 124. The condensing positionderiving portion 124 a of the measuring portion 124 acquires theirradiation distance information output by the irradiation distance dataacquiring portion 122 a and acquires an inter-lens distance between thelens 12 c and the lens 12 d associated with the acquired irradiationdistance information from the inter-lens distance table 144 stored inthe storing portion 140.

The condensing position deriving portion 124 a determines whether or notthe acquired distance is within an available condensing distance rangeof the lenses 12 a, 12 b, 12 c, and 12 d.

(Step S504)

The condensing position deriving portion 124 a outputs an error when itis determined that the acquired distance is not within the availablecondensing distance range. The condensing position deriving portion 124a may display that there is an error on the display portion 130.

(Step S505)

The condensing position deriving portion 124 a determines whether or notto continue the inspection. When the inspection is continued, theprocess proceeds to step S501. When the inspection is not continued, theprocess ends.

(Step S506)

When it is determined that the acquired distance is within the availablecondensing distance range in step S503, steps S101 to S111 of FIG. 14are executed.

(Step S507)

Steps S201 to S204 of FIG. 15 are executed.

(Step S508)

The irradiation location analyzing portion 124 b of the processing unit100 determines whether or not there is a location where laserirradiation is possible. When there is no location where laserirradiation is possible, the process proceeds to step S504.

(Step S509)

When it is determined that there is no location where laser irradiationis possible in step S508, steps S205 to S206 of FIG. 15 are executed.

(Step S510)

The irradiation location analyzing portion 124 b of the processing unit100 determines whether or not there is a location where dirt or moistureis significantly different from that of other locations.

(Step S511)

When it is determined that there is a location where dirt or moisture issignificantly different from that of other locations in step S510, theirradiation location analyzing portion 124 b displays a warning on thedisplay portion 130.

(Step S512)

When it is determined that there is no location where dirt or moistureis significantly different from that of other locations in step S510,the irradiation location analyzing portion 124 b determines whether ornot there is a sweep route for avoiding a location where laserirradiation is not possible. When there is no sweep route for avoiding alocation where laser irradiation is not possible, the process ends.

(Step S513)

After the warning is displayed on the display portion 130 in step S511or when there is a sweep route for avoiding a location where laserirradiation is not possible in step S512, the excitation laser device 1radiates excitation laser light and the measurement laser device 2radiates measurement laser light.

A process may be executed in a state in which any one of steps S501 toS513 is omitted or the order of steps S501 to S513 may be changed.

(Operation of Laser-Induced Vibration Wave Measuring System 20)

FIG. 31 is a sequence chart showing an example of an operation of thelaser-induced vibration wave measuring system of the first embodiment.FIG. 31 shows a process of determining whether or not a location of theinspection target M irradiated with excitation laser light is faultlessby controlling an output timing of the excitation laser light, radiatingthe excitation laser light and measurement laser light, and processingvibration data. That is, a process in which FIGS. 16 and 17 of the firstembodiment are linked will be described. Here, FIGS. 2, 16, and 17 areappropriately referred to.

(Step S601)

The reverberation sound analyzing portion 124 c of the processing unit100 designates a measurement range 50-1.

(Step S602)

The reverberation sound analyzing portion 124 c of the processing unit100 designates the number of irradiation pulses p of the measurementlaser light.

(Step S603)

The reverberation sound analyzing portion 124 c of the processing unit100 designates a number a which is the number of measurement areas 203.

(Step S604)

Steps S301 to S307 of FIG. 16 are executed.

(Step S605)

The reverberation sound analyzing portion 124 c of the processing unit100 determines whether or not there is a time period in which echo noiseis reduced.

(Step S606)

The reverberation sound analyzing portion 124 c outputs an error when itis determined that there is no time period in which echo noise isreduced. The reverberation sound analyzing portion 124 c may display anerror on the display portion 130.

(Step S607)

The reverberation sound analyzing portion 124 c determines whether ornot to continue the inspection. When the inspection is continued, theprocess proceeds to step S601.

(Step S608)

When the inspection is not continued, the display portion 130 displays aresult of inspecting the faultlessness of a portion of the inspectiontarget M irradiated with the excitation laser light.

(Step S609)

When it is determined that there is a time period in which echo noise isreduced in step S605, the timing deriving portion 124 d sets i=0.

(Step S610)

The timing deriving portion 124 d sets j=1.

(Step S611)

The timing deriving portion 124 d determines whether or not i>p.

(Step S612)

When i≥p, the excitation laser device 1 radiates the excitation laserlight and the measurement laser device 2 radiates the measurement laserlight.

(Step S613)

The communicating portion 110 of the processing unit 100 receivesvibration data (the number of vibrations) transmitted by the measurementlaser device 2 and outputs the received vibration data to theinformation acquiring portion 122. The vibration data acquiring portion122 d of the information acquiring portion 122 acquires the vibrationdata output by the communicating portion 110.

The vibration data acquiring portion 122 d outputs the acquiredvibration data to the analyzing portion 126.

(Step S614)

The timing deriving portion 124 d sets i=i+1 and returns to step S611.

(Step S615)

Steps S401 to S404 of FIG. 17 are executed.

(Step S616)

The data processing portion 126 a determines whether or not j>a. Whenj>a, the process proceeds to step S607.

(Step S617)

The timing deriving portion 124 d causes the measurement area to bemoved. For example, the timing deriving portion 124 d causes themeasurement area to be moved from the biaxial mirror irradiation area203-1 to the biaxial mirror irradiation area 203-2.

(Step S618)

The timing deriving portion 124 d sets j=j+1 and proceeds to step S611.

A process may be executed in a state in which any one of steps S601 toS609 is omitted or the order of steps S601 to S609 may be changed.

Although the operation of the laser-induced vibration wave measuringsystem 20 according to the first embodiment has been described here asan example, the present invention is not limited thereto. For example,likewise, the present invention is not limited to the operation of thelaser-induced vibration wave measuring system 20 a of the secondembodiment or the modified example of the laser-induced vibration wavemeasuring system 20 of the first embodiment or the laser-inducedvibration wave measuring system 20 a of the second embodiment.

While several embodiments of the present invention have been described,these embodiments have been presented by way of example only, and arenot intended to limit the scope of the inventions. These embodiments maybe embodied in a variety of other forms. Various omissions,substitutions, changes, and combinations may be made without departingfrom the spirit of the inventions. The inventions described in theaccompanying claims and their equivalents are intended to cover suchembodiments or modifications as would fall within the scope and spiritof the inventions.

Also, the above-described processing units 100 and 100 a internally havea computer. The process of processing of each device described above isstored in a computer-readable recording medium in the form of a programand the above-described processing is performed by the computer readingand executing the program. Here, the computer-readable recording mediumrefers to a magnetic disc, a magneto-optical disc, a CD-ROM, a DVD-ROM,a semiconductor memory, or the like. Also, the computer program may bedistributed to the computer via a communication circuit and the computerreceiving the distributed computer program may execute the program.

Also, the above-described program may be a program for implementing someof the above-described functions.

Further, the above-described program may be a program capable ofimplementing the above-described function in combination with a programalready recorded on the computer system, i.e., a so-called differentialfile (differential program).

In the above-described embodiment, the processing unit 100 and theprocessing unit 100 a are examples of a measuring device, the inspectiontarget M is an example of an inspection target, the excitation laserlight is an example of a laser, the data processing portion 126 a andthe data processing portion 126 c are examples of a data removingportion and a noise removing portion, the galvano scanner unit 3 and thebiaxial mirror unit 5 are examples of a sweep device, the excitationlaser device is an example of a laser device, and the galvano scannerunit 3 and the biaxial mirror unit 5 are an example of a sweep portion.

REFERENCE SIGNS LIST

-   20, 20 a Laser-induced vibration wave measuring system-   1 Excitation laser device-   2 Measurement laser device-   3 Galvano scanner unit-   4 a, 4 b Galvano scanner mirror-   5 Biaxial mirror unit-   6 Biaxial mirror-   7 Reverberation sound monitor-   8 a, 8 b, 8 c Mirror-   9 Distance measurement laser device-   10 Excitation laser condensing unit-   11 Measurement laser condensing unit-   12 a, 12 b, 12 c, 12 d Lens-   13 Imaging device-   100, 100 a Processing unit-   110 Communicating portion-   120, 120 a Information processing portion-   122 Information acquiring portion-   122 a Irradiation distance data acquiring portion-   122 b Irradiation location data acquiring portion-   122 c Reverberation sound data acquiring portion-   122 d Vibration data acquiring portion-   124 Measuring portion-   124 a Condensing position deriving portion-   124 b Irradiation location analyzing portion-   124 c Reverberation sound analyzing portion-   124 d Timing deriving portion-   126, 126 d Analyzing portion-   126 a, 126 c Data processing portion-   126 b Determining portion-   140, 140 a Storing portion-   142, 142 a Program-   144 Inter-lens distance table-   146 Surrounding measurement data DB-   250 Equipment storage-   300 Device housing-   400 Biaxial mirror housing-   500 Truck

What is claimed is:
 1. A measuring device for measuring an inspectiontarget on the basis of vibration generated when the inspection targethas been irradiated with laser light, the measuring device comprising: acondensing position deriving portion configured to derive an amount ofadjustment of a condensing position of a laser condensing unitconfigured to condense the laser light on the basis of a distancebetween a laser device configured to radiate the laser light and anirradiation location of the laser light; an irradiation locationanalyzing portion configured to select a location to be irradiated withthe laser light on the basis of information representing an image of alocation of the inspection target scheduled to be irradiated with thelaser light; and a communicating portion configured to transmit controlinformation including information representing the amount of adjustmentto the laser condensing unit, wherein the irradiation location analyzingportion configured to select a route having the shortest length fromamong routes for radiating laser light represented by the connectedline, when all selected scheduled laser irradiation locations areconnected and wherein the communicating portion is configured totransmit control information including information representing thelocation to be irradiated with the laser light selected by theirradiation location analyzing portion to a sweep device configured tosweep the laser light.
 2. The measuring device according to claim 1,wherein the irradiation location analyzing portion is configured toselect the shortest route under the assumption that the laser light isblocked by the physical shutter so that the appendage is not irradiatedwith the laser light, when there is a route that passes over theappendage.
 3. The measuring device according to claim 1, furthercomprising: a reverberation sound data acquiring portion configured toacquire time-series data of a reverberation sound generated when theinspection target has been irradiated with the laser light; and areverberation sound analyzing portion configured to acquire a timing atwhich the inspection target is irradiated with the laser light on thebasis of an intensity of the reverberation sound of the time-series dataof the reverberation sound acquired by the reverberation sound dataacquiring portion, wherein the communicating portion is configured totransmit control information including the information representing thetiming acquired by the reverberation sound analyzing portion to thelaser device configured to radiate the laser light.
 4. The measuringdevice according to claim 1, further comprising a data removing portionconfigured to remove data during a predetermined time period from a timeat which the inspection target has been irradiated with the laser lightfrom measurement data of vibration generated in the inspection target.5. The measuring device according to claim 1, further comprising a noiseremoving portion configured to remove noise from measurement data on thebasis of a correlation coefficient between the measurement data ofvibration generated in the inspection target and an evaluation functionof the measurement data.
 6. The measuring device according to claim 1,further comprising a noise removing portion configured to remove noisefrom measurement data of vibration on the basis of the measurement dataof the vibration generated in the inspection target and data obtained byshifting a phase of time-series data of the measurement data.
 7. Themeasuring device according to claim 1, further comprising a determiningportion configured to determine faultlessness of a location of theinspection target irradiated with the laser light on the basis ofmeasurement data acquired when vibration has been induced in theinspection target by irradiating the inspection target with the laserlight and measurement data acquired when the inspection target has notbeen irradiated with the laser light that induces the vibration.
 8. Themeasuring device according to claim 1, wherein at least the lasercondensing unit is stored in a housing having soundproofing performance.9. A measuring system for measuring an inspection target on the basis ofvibration generated when the inspection target has been irradiated withlaser light, the measuring system comprising: an excitation laser deviceconfigured to radiate excitation laser light, which is the laser lightthat causes the inspection target to vibrate; an excitation lasercondensing unit configured to condense the excitation laser lightradiated by the excitation laser device; and a measuring deviceincluding a condensing position deriving portion configured to derive afirst amount of adjustment of a condensing position of the excitationlaser condensing unit on the basis of a distance between the excitationlaser device and an irradiation location of the excitation laser lightradiated by the excitation laser device; an irradiation locationanalyzing portion configured to select a location to be irradiated withthe laser light on the basis of information representing an image of alocation of the inspection target scheduled to be irradiated with thelaser light; and a communicating portion configured to transmit controlinformation including information representing the first amount ofadjustment to the excitation laser condensing unit, wherein theirradiation location analyzing portion configured to select a routehaving the shortest length from among routes for radiating laser lightrepresented by the connected line, when all selected scheduled laserirradiation locations are connected and wherein the communicatingportion is configured to transmit control information includinginformation representing the location to be irradiated with the laserlight selected by the irradiation location analyzing portion to a sweepdevice configured to sweep the laser light.
 10. The measuring systemaccording to claim 9, comprising: a measurement laser device configuredto irradiate the inspection target with measurement laser light that islaser light for detecting vibration induced in the inspection target;and a measurement laser condensing unit configured to condense themeasurement laser light radiated by the measurement laser device,wherein the condensing position deriving portion derives a second amountof adjustment of a condensing position of the measurement lasercondensing unit on the basis of a distance between the measurement laserdevice and an irradiation location of the measurement laser lightradiated by the measurement laser device and wherein the communicatingportion is configured to transmit control information includinginformation representing the second amount of adjustment to themeasurement laser condensing unit.
 11. The measuring system according toclaim 10, comprising a sweep device configured to sweep the excitationlaser light output by the excitation laser device and the measurementlaser light output by the measurement laser light device.
 12. Themeasuring system according to claim 9, wherein at least the excitationlaser condensing unit is stored in a housing having soundproofingperformance.
 13. A moving body equipped with the measuring systemaccording to claim
 9. 14. A measuring method to be executed by ameasuring device for measuring an inspection target on the basis ofvibration generated when the inspection target has been irradiated withlaser light, the measuring method comprising steps of: deriving anamount of adjustment of a condensing position of a laser condensing unitconfigured to condense the laser light on the basis of a distancebetween a laser device configured to radiate the laser light and anirradiation location of the laser light; transmitting controlinformation including information representing the amount of adjustmentto the laser condensing unit; selecting a location to be irradiated withthe laser light on the basis of information representing an image of alocation of the inspection target scheduled to be irradiated with thelaser light; selecting a route having the shortest length from amongroutes for radiating laser light represented by the connected line, whenall selected scheduled laser irradiation locations are connected; andtransmitting control information including information representing thelocation to be irradiated with the laser light selected by theirradiation location analyzing portion to a sweep device configured tosweep the laser light.
 15. The measuring method according to claim 14,further comprising steps of: selecting the shortest route under theassumption that the laser light is blocked by the physical shutter sothat the appendage is not irradiated with the laser light, when there isa route that passes over the appendage.
 16. The measuring methodaccording to claim 14, further comprising steps of: acquiringtime-series data of a reverberation sound generated when the inspectiontarget has been irradiated with the laser light at a certain timing;acquiring a timing at which the inspection target is irradiated with thelaser light on the basis of an intensity of the reverberation sound ofthe time-series data of the reverberation sound; and transmittingcontrol information including the information representing the timing tothe laser device configured to radiate the laser light.
 17. Themeasuring method according to claim 14, further comprising a step ofremoving data during a predetermined time period from a time at whichthe inspection target has been irradiated with the laser light frommeasurement data of vibration generated in the inspection target. 18.The measuring method according to claim 14, further comprising a step ofremoving noise from measurement data on the basis of a correlationcoefficient between the measurement data of vibration generated in theinspection target and an evaluation function of the measurement data.19. The measuring method according to claim 14, further comprising astep of removing noise from measurement data of vibration on the basisof the measurement data of the vibration generated in the inspectiontarget and data obtained by shifting a phase of time-series data of themeasurement data.
 20. The measuring method according to claim 14,further comprising a step of determining faultlessness of a location ofthe inspection target irradiated with the laser light on the basis ofmeasurement data acquired when vibration has been induced in theinspection target by irradiating the inspection target with the laserlight and measurement data acquired when the inspection target has notbeen irradiated with the laser light that induces the vibration.